Method and device for blow-molding containers which are sterile at least in some areas

Abstract

A method and a device for producing blow-molded containers, which are sterile at least in some areas, in a blow-molding machine. A preform made of a thermoplastic material is first heated, then stretched by a stretching rod in a blowing station, and then supplied with a pressurized fluid via a blow nozzle, wherein a sterilization device is arranged in the blowing station. The sterilization device has at least one radiation source which emits a sterilizing radiation onto the stretching rod and/or onto the blow nozzle.

Claims

1. A device for manufacturing blow-molded containers which are sterile in at least some areas, that device comprising: a heating section for temperature controlling preforms of a thermoplastic material; at least one blowing station for blow-molding the preforms to form containers, wherein a blowing station of the at least one blowing station has a stretching rod for stretching a preform of the preforms and a blowing nozzle for impinging the preform with a pressurized fluid; and a sterilization installation disposed in the blowing station, wherein the sterilization installation has at least one radiation source that emits a sterilizing radiation onto the stretching rod and/or onto the blowing nozzle, wherein the at least one radiation source is arranged outside of a blow mold and is disposed so as to be positionally fixed in relation to the blowing station such that the at least one radiation source emits radiation onto a side of the blowing nozzle that faces the preform and/or onto a mouth area of the preform.

2. The device as claimed in claim 1, wherein the sterilization installation is actuatable to emit sterilizing radiation during blow-molding and/or during an inline operation and/or during start-up of the device.

3. The device as claimed in claim 1, wherein the at least one radiation source is configured as a UV radiation emitting UV radiation source.

4. The device as claimed in claim 3, wherein the stretching rod is made of a UV radiation conducting material.

5. The device as claimed in claim 4, wherein the stretching rod is made of a quartz glass.

6. The device as claimed in claim 1, wherein the stretching rod has at least one internal duct that is connected in a valve-controlled manner to a source or sink for ionized air and/or to a source or sink for a chemical sterilization agent, so as to route ionized air and/or the chemical sterilization agent through the at least one internal duct into the preform and/or out of the preform.

7. The device as claimed in claim 1, wherein the at least one radiation source is disposed so as to be fixed in height in relation to the blowing station in so that the stretching rod and/or the blowing nozzle during a height-positioning movement thereof are moved past the at least one radiation source.

8. The device as claimed in claim 7, wherein the at least one blowing station comprised of a plurality of blowing stations which are disposed on a rotating blowing wheel and each blowing station of the plurality of blowing stations has a conjointly rotating sterilization installation.

9. The device as claimed in claim 1, wherein the at least one radiation source is disposed on the blowing nozzle such that the at least one radiation source emits radiation onto the stretching rod and/or onto the mouth area of the preform and/or onto a blowing nozzle area that comes into contact with the preform.

10. The device as claimed in claim 1, wherein the at least one radiation source is configured so as to be centrically symmetrical which surrounds an area to be sterilized in an annular manner, and emits the sterilizing radiation into an annular interior.

11. The device as claimed in claim 1, further comprising sterile air outlets in an area of the blowing station, the sterile air outlets being supplied with sterile air and being disposed and configured so that sterile air for configuring a sterile air curtain is blown down around the blowing nozzle.

12. The device as claimed in claim 11, wherein the sterile air outlets are disposed and configured to blow down the sterile air curtain in a laminar flow along the blowing nozzle or proceeding from the blowing nozzle in a direction of the preform.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 shows a perspective illustration of a blowing station for manufacturing containers from preforms;

(2) FIG. 2 shows a longitudinal section through a blow mold in which a preform is stretched and expanded;

(3) FIG. 3 shows a diagram to visualize an in-principle construction of a device for blow-molding containers;

(4) FIG. 4 shows a modified heating section having an increased heating capacity;

(5) FIG. 5 shows a schematic illustration of a preform having a stretching rod extended thereinto, according to a first and a second exemplary embodiment;

(6) FIG. 6 shows a schematic illustration of a preform received in a blow mold, having a retracted stretching rod and a blowing nozzle which is disposed for impingement with blowing air;

(7) FIG. 7 shows in a schematic illustration two blowing stations, shown in an exemplary manner, on a rotating blowing wheel having a sterilizing installation, according to a first and a second exemplary embodiment; and

(8) FIG. 8 shows in a schematic sectional illustration an arrangement of the sterilizing installation within a blowing station.

DETAILED DESCRIPTION OF THE INVENTION

(9) The in-principle construction of a device for forming preforms 1 into containers 2 is illustrated in FIGS. 1 and 2.

(10) The device for molding the container 2 is substantially composed of a blowing station 3 which is provided with a blow mold 4 into which a preform 1 is insertable. The preform 1 may be an injection-molded part made from polyethylene terephthalate. In order to enable insertion of the preform 1 into the blow mold 4, and in order to enable removal of the finished container 2, the blow mold 4 is composed of two mold halves 5, 6, and of a base part 7 which is positionable by a lifting device 8. The preform 1 in the area of the blowing station 3 may be held by a conveying mandrel 9 which together with the preform 1 passes through a plurality of treatment stations within the device. However, it is also possible for the preform 1 to be inserted directly into the blow mold 4 by way of tongs or other handling means, for example.

(11) In order for a compressed-air supply line to be enabled, a blowing nozzle 10 which supplies compressed air to the preform 1 and at the same time performs sealing toward the conveying mandrel 9 is disposed below the conveying mandrel 9. However, in the case of a modified construction it is also conceivable that fixed compressed-air supply lines are used.

(12) Stretching of the preform 1 is performed with the aid of a stretching rod 11 which is positioned by a cylinder 12. However, in-principle it is also conceivable for mechanical positioning of the stretching rod 11 to be carried out by curved segments which are impinged by tapping rollers. The use of curved segments is expedient in particular when a plurality of blowing stations 3 are disposed on a rotating blowing wheel. Use of cylinders 12 is expedient when blowing stations 3 which are disposed in a locationally fixed manner are provided.

(13) In the embodiment illustrated in FIG. 1 the stretching system is configured in such a manner that a tandem arrangement of two cylinders 12 is provided. Prior to commencement of the stretching procedure per se, the stretching rod 11 is initially moved by a primary cylinder 13 into the area of a base 14 of the preform 1. During the stretching procedure per se the primary cylinder 13 having the extended stretching rod, together with a slider 15 which supports the primary cylinder 13, is positioned by a secondary cylinder 16 or by way of a cam control unit. In particular, it is contemplated that the secondary cylinder 16 is employed in a cam-controlled manner such that a current stretching position is predefined by a guide roller 17 which slides along a curved track while the stretching procedure is carried out. The guide roller 17 is pressed against the guide track by the secondary cylinder 16. The slider 15 slides along two guide elements 18. After the mold halves 5, 6 which are disposed in the area of supports 19, 20 have been closed, mutual interlocking of the supports 19, 20 with the aid of an interlocking installation 40 is performed.

(14) In order for a mouth portion 21 of the preform 1 to be adapted to various shapes, the use of separate threaded inserts 22 is provided according to FIG. 2 in the area of the blow mold 4.

(15) In addition to the blown container 2, FIG. 2 also shows the preform 1 having dashed lines and in a schematic manner a container bubble 23 under formation.

(16) FIG. 3 shows the in-principle construction of a blowing machine which is provided with a heating section 24 as well as a rotating blowing wheel 25. Proceeding from a preform infeed 26, the preforms 1 are conveyed into the area of the heating section 24 by transfer wheels 27, 28, 29. Heating radiators 30 and blowers 31 are disposed along the heating section 24, so as to temperature control the preforms 1. After sufficient temperature control of the preforms 1, the latter are transferred to the blowing wheel 25, the blowing stations 3 being disposed in the area thereof. The blown finished containers 2 are supplied to a delivery section 32 by further transfer wheels.

(17) In order to be able to form a preform 1 into a container 2 in such a manner that the container 2 has material properties which guarantee a prolonged shelf life of foodstuffs, in particular beverages, which are filled into the container 2, special method steps must be adhered to when heating and orienting the preforms 1. Moreover, advantageous effects may be achieved by adhering to special dimensioning rules.

(18) Various plastics may be used as the thermoplastic material. PET, PEN, or PP are employable, for example.

(19) Expanding the preform 1 during the orientation procedure is performed by supplying compressed air. The compressed-air supply is subdivided into a pre-blowing phase in which gas, for example compressed air, is supplied at a low pressure level, and into a subsequent main blowing phase in which gas is supplied at a comparatively high pressure level. During the pre-blowing phase, compressed air at a pressure in the range of 10 bar to 25 bar is typically used, and during the main blowing phase, compressed air at a pressure in the range of 25 bar to 40 bar is supplied.

(20) It can likewise be seen in FIG. 3 that the heating section 24 in the embodiment illustrated is configured from a plurality of revolving conveying elements 33 which are strung together in a chain-like fashion and are guided along by deflection wheels 34. In particular, it is contemplated that a substantially rectangular basic contour is defined by the chain-like arrangement. In the case of the embodiment illustrated, a single deflection wheel 34 which is of comparatively large size is used in the area of that extent of the heating section 24 that faces the transfer wheel 29 and an infeed wheel 35, and two deflection wheels 36 which are of comparatively small size are used in the area of adjacent deflections. However, other guides are also conceivable in principle.

(21) In order for as tight a mutual arrangement of the transfer wheel 29 and of the infeed wheel 35 as possible to be enabled, the arrangement illustrated has proven particularly expedient, since three deflection wheels 34, 36, are positioned in the area of the respective extent of the heating section 24, and specifically in each case the comparatively small deflection wheels 36 in the area of the transition toward the linear profiles of the heating section 24, and the comparatively large deflection wheel 34 in the immediate transfer area to the transfer wheel 29 and to the infeed wheel 35. As an alternative to the use of chain-like conveying elements 33, it is also possible for a rotating heating wheel to be used, for example.

(22) After blowing of the containers 2 has been completed, the latter are guided out of the area of the blowing stations 3 by a retrieval wheel 37 and by way of the transfer wheel 28 and a delivery wheel 38 are conveyed to the delivery section 32.

(23) On account of the higher number of heating radiators 30, a larger amount of preforms 1 per unit of time may be temperature controlled in the modified heating section 24 illustrated in FIG. 4. The blowers 31 here direct cooling air into the area of cooling air ducts 39 which in each case lie opposite the assigned heating radiators 30 and discharge the cooling air via outflow openings. On account of the arrangement of the outflow directions, a streaming direction for the cooling air that is substantially transverse to a conveying direction of the preforms 1 is implemented. The cooling air ducts 39 in the area of those surfaces that lie opposite the heating radiators 30 may provide reflectors for the radiation of heat; it is likewise possible for cooling of the heating radiators 30 to be implemented by way of the dissipated cooling air.

(24) In a schematic and very simplified manner, FIG. 5 shows two exemplary embodiments for the configuration of a sterilization installation in a blowing station. In order for the illustration to be simplified, only the preform 1 is shown. It is not shown, in particular, that this preform 1 is received in a blow mold. Further parts of the blowing station which are not relevant to the explanation of this exemplary embodiment have likewise been omitted for the sake of simplification.

(25) The right half of FIG. 5 shows a stretching rod 11 which in a known fashion is manufactured from a metallic material, for example. In order for the preform 1 to be stretched, the stretching rod 11 is positioned in terms of height. To this end, a lifting device (not illustrated) such as has been explained in the context of FIG. 1, for example, is provided. A plurality of UV emitters 51 which emit UV radiation 52 in the direction of the stretching rod 11 are disposed in a height-specific area of the stretching rod 11. On account of this UV radiation 52, the stretching rod 11 in the irradiated area is de-germed or kept germ-free, respectively. In the stretching procedure or during height-specific positioning of the stretching rod 11, respectively, the stretching rod 11 travels through the UV emitters 51 which are disposed on opposite sides and, on account thereof, a new area of the stretching rod 11 is continuously irradiated by UV radiation 52. Height-specific positioning of the UV emitters 51 here is preferably chosen such that the stretching rod 11, commencing with the stretching rod tip 53, in the course of the height-related movement thereof is swept with UV radiation 52. In this way, that entire area of the stretching rod 11 that during the stretching process is driven into the preform 1 is reliably impinged with UV radiation 52. The UV emitter 51 may be configured so as to be annular, for example. However, a plurality of UV emitters 51 which surround the stretching rod 11 in an annular manner may also be provided. The state illustrated corresponds approximately to the point in time at which the stretching rod tip 53 comes to bear on the preform base 14 and begins to exert a stretching force.

(26) The left half of FIG. 5 shows an embodiment of the invention which in relation to the right half is modified. In this left half, the stretching rod 11 is manufactured from a material which conducts UV radiation. The configuration from a quartz glass is contemplated here in particular. As has also been set forth with reference to the right half of FIG. 5, UV emitters 51 which emit UV radiation 52 in the direction of the stretching rod 11 are disposed in a height-specific area of the stretching rod 11. On account of the configuration of the stretching rod being of a quartz glass, for example, the UV radiation 52 may enter into the stretching rod 11. The UV radiation 52 is routed within the stretching rod 11, in particular in the direction of the preform 1, and via the stretching-rod surface and via a height-specific area h of the stretching rod 11 exits from the latter and in particular impacts the internal surface 54 of the preform 1.

(27) Routing the UV radiation 52 within the stretching rod 11 may be supported in that launching means (not illustrated) are provided, so as to launch the UV radiation 52 into the stretching rod 11 in a targeted manner. For example, a reflecting mirror, a prism, or similar, could be disposed in a launching area. The UV radiation 52 could also be infed into the stretching rod 11 from the outside by means of UV-conducting optical fibers, for example. Means which facilitate the emission of UV radiation may also be provided in the stretching rod 11 or on the stretching rod. For example, diffuser bodies may be provided along a length area h of the stretching rod 11 in the material of the stretching rod, or the surface of the stretching rod 11 by way of a facet cut may be configured for targeted emission. Preferably, the stretching rod 11 emits UV radiation 52 along a length area h which, commencing at the stretching rod tip 53, runs up to a height which corresponds to the height up to which the stretching rod 11 is immersed when being driven into the preform 1 up to contact with the base area 14 of the preform 1. However, the emission area may also be longer, so as to release UV radiation 52 during the stretching process as far as possible along the entire height-specific area of the container 2 under development, for example.

(28) As a further modification in relation to the right half of FIG. 5, the stretching rod 11 in the left half of FIG. 5 has a central bore 55 through which ionized air 56 may be blown into the preform 1, so as to blow out contaminations from the preform 1, for example. By way of this internal duct 55, hydrogen peroxide 57 or another suitable chemical sterilizing means, for example in the gaseous aggregate state, may be introduced into the preform 1, so as to bring about additional sterilizing. It is also conceivable for this internal duct 55 to be used not for infeeding the mentioned media but for discharging, that is to say that the ionized air 56 or the gaseous hydrogen peroxide 57, respectively, could be discharged from the preform 1 by way of this internal duct 55. In a fashion not illustrated, the stretching rod 11 may also have a plurality of internal ducts 55 which then are usable both for the supply and for the discharge of the media, for example. It is also possible for ionized air 56 to be supplied or discharged, respectively, by way of one of the ducts 55 and for hydrogen peroxide 57 to be supplied and discharged, respectively, by way of another of the ducts 55. It is also conceivable for all ducts 55 to the used in the same way for the supply and/or for the discharge of the mentioned media. These variants may all also be transferred to the stretching rod 11 of the right half of the picture.

(29) FIG. 6 in a very schematic illustration shows a further exemplary embodiment of the invention. A blowing nozzle 10 which serves for supplying blowing air, as has already been explained by means of FIG. 1, for example, is shown. It is provided according to the invention that UV emitters 60 are disposed within the blowing nozzle 10. These UV emitters 60 here are disposed such that the emission of the UV radiation 61 is performed in the direction of the stretching rod 11. At the same time, the neck area 21 of the preform 1 is irradiated, and the interior 62 of the blowing nozzle 10 is also impinged with UV radiation 61. Here too, the UV emitters 60 may be disposed in an annular manner or be configured in an annular manner. On account of the relative movement between the blowing nozzle 10 and the stretching rod 11, a specific length area of the stretching rod 11 is illuminated by UV radiation 61, said specific length area commencing at the stretching rod tip 53 and running up to a terminal position of the stretching rod 11. Additionally, further UV emitters 51 which emit UV radiation 52 in the direction of the stretching rod 11 are disposed outside and above the blowing nozzle 10. To this end, reference may be made to FIG. 5.

(30) FIG. 7 in a very schematic illustration shows a blowing wheel 25 having two blowing stations 3 which are illustrated in an exemplary manner and have in each case two blow mold halves 5, 6. The blowing station 3 which is shown at the 6 o'clock position of the blowing wheel 25 has UV emitters 70 which surround the blowing nozzle 10 in an annular manner. These emitters 70 are disposed and aligned such that the blowing nozzle 10 is impinged with UV radiation 71. Preferably, the UV emitters 70 are aligned such that the lower area of the blowing nozzle 10, which faces the preform 1, is irradiated, in particular that area that comes into contact with the preform 1. As soon as the blowing nozzle 10 commences the lowering movement thereof in order to be lowered in a sealing manner onto the preform 1, the adjacent area of the blowing nozzle 10 is also irradiated with UV radiation 71.

(31) The blowing station 3 which is shown in the 4 o'clock position of the blowing wheel 25 has UV emitters 73 which are disposed in a stationary manner and in terms of height are positioned and aligned such that the blowing nozzle 10 which is being moved past is irradiated with UV radiation 74. Here too, irradiation of that side of the blowing nozzle 10 that faces the preform 1 is preferably performed.

(32) FIG. 8 in a schematic sectional illustration shows the arrangement of UV emitters 80 on a fixed part of the blowing station 3. It can be seen that the UV radiation 81 not only impinges the lower side 82 of the blowing nozzle 10 but also the neck area 21 of the preform 1. As soon as the stretching rod (not illustrated) is positioned through the blowing nozzle 10 in the direction of the preform 1, the stretching rod 11 is also irradiated with UV light. All areas which are relevant to reliable sterilizing or sterile keeping are covered with sterilizing radiation in the fashion narrated.