Blow molding machine with CIP system for producing plastic bottles, particularly PET bottles

A blow molding machine for producing plastic bottles, particularly PET bottles, including a plurality of blow molding stations, which have assigned thereto valve blocks with control valves and blowing nozzles for introducing or discharging blowing air; and a cleaning-in-place (CIP) system for cleaning the blow molding machine. Since the valve blocks are configured such that they can be included in the CIP process, the system components, such as the blowing nozzle, which are particularly important for the production of PET bottles in terms of hygiene, can be cleaned and sterilized without disassembly.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority of German Application No. 102009023406.3, filed May 29, 2009. The entire text of the priority application is incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure refers to a blow molding machine for producing plastic bottles, particularly PET bottles, and to a method for the cleaning in place of a blow molding machine.

BACKGROUND

The so-called “cleaning in place”, also called CIP, is a known method for sterilizing production plants in the food industry, wherein a disassembly of the areas contacted by the product or the intermediate products and auxiliary means can substantially be dispensed with. So far the CIP sterilization of blow molding machines for beverage bottles, as in DE 200 18 500 U1, has however not been possible because the cleaning agents which are normally used for sterilization, e.g. hydrogen peroxide or peracetic acid, attack the pneumatic units of such blow molding machines.

The cleaning and sterilization needed instead of this with partial disassembly of the blow molding machine is time-consuming and responsible for an undesired long standstill time of the machine.

SUMMARY OF THE DISCLOSURE

It is therefore an aspect of the present disclosure to provide a blow molding machine which can be sterilized more easily and faster. A method for cleaning the same is also needed.

This aspect is achieved in that the valve blocks of the blow molding machine are configured such that they can be included in the CIP process.

It is thereby possible to clean and sterilize the system components, such as the blowing nozzle, which are particularly critical in terms of hygiene for the production of PET bottles, substantially without any disassembly.

Preferably, the valves must be operated pneumatically. The blow molding machine can thus be controlled in a reliable and inexpensive way.

In a particularly advantageous development of the invention, CIP shut-off valves for shutting off pneumatic control lines of the control valves are provided on the valves. It can thereby be prevented that aggressive CIP agents can pass through the control line to further control valves and/or into a compressed air network.

Preferably, the valves comprise seals that are resistant to sterilizing CIP agents, particularly to hydrogen peroxide, peracetic acid, alcohol and soap suds. This enables an uncomplicated repeatable cleaning of the valves.

Control valves are conventionally also called pilot valves.

In a particularly advantageous embodiment, the CIP system comprises: a processing unit for circulating and processing a CIP agent; a CIP feed line for the cleaning agent that can be connected to a blowing-air feed line for the control valves; and removable CIP sealing caps for collecting the cleaning agent at the blow molding stations, with the CIP sealing caps being connected to a CIP return line for returning the cleaning agent into the processing unit. As a result, the cleaning agent can be collected entirely and run in a circuit.

Preferably, the blow molding machine further comprises a media distributor for distributing the blowing air over the blow molding stations and for collecting the cleaning agent and for introducing the collected cleaning agent into the CIP return line. As a consequence, the blowing air and the cleaning agent can be distributed in a space-saving way and the blow molding machine can be rapidly changed over from production operation to CIP, and vice versa.

Preferably, a CIP main shut-off valve is provided in the CIP feed line. This valve prevents blowing air from penetrating into the processing unit in the production process and/or cleaning agent from penetrating into the blowing-air stream.

Preferably, a shut-off valve for the blowing air is provided in the blowing-air feed line. Said valve prevents cleaning agent from penetrating into a blowing-air compressor during CIP and/or blowing air from exiting into the CIP circuit.

The problem is also solved with a method for the CIP of the blow molding machine according to the invention, wherein in a step a) a CIP agent is passed through the valve blocks of the blow molding stations, including the valves and the blowing nozzles. System components of the blow molding machine, e.g. the blowing nozzle, which are particularly critical in terms of hygiene for the production of PET bottles, can thus be cleaned and sterilized without disassembly.

Preferably, the CIP method further comprises the following step b): shutting off pneumatic control lines of the control valves, wherein step b) is carried out before step a). Aggressive CIP agents can thus not pass through the control line to further control valves and/or into a compressed air network.

In a particularly advantageous design, the CIP cleaning method further comprises the following step c): connecting a CIP feed line for the cleaning agent with at least one blowing-air feed line to the valves, wherein step c) is carried out before step a). The existing blowing-air channels can thus be cleaned and used for introducing the cleaning agent into the blowing nozzle.

Preferably, the method comprises the following step d): shutting off a section of the blowing-air feed line at the compressor side, wherein step d) is carried out before step a). In the CIP process this prevents cleaning agents from penetrating into a blowing-air compressor and/or blowing air from exiting into the CIP circuit.

Preferably, the method further comprises the following step: collecting the cleaning agent passed through the valve blocks and returning the cleaning agent into a CIP circuit. This prevents the uncontrolled exit of cleaning agent or its dissipation, respectively.

A particularly advantageous configuration of the method comprises the following step: processing the returned cleaning agent and feeding the processed cleaning agent into the CIP circuit. The cleaning agent can thus be used repeatedly with the same cleaning quality. This saves costs and is environmentally friendly.

Preferably, a sterilizing cleaning agent is passed through the valve blocks, particularly hydrogen peroxide, peracetic acid, alcohol and soap suds. The sterilizing process can thus be carried out in the well-established way for beverage systems, particularly with cleaning agents that are also used for sterilizing preforms.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As can be seen inFIG. 1, the blow molding machine1is configured in the embodiment in the known way as a rotary machine with a plurality of blow molding stations2arranged in symmetry around a rotational axis1′ and used for producing plastic bottles3, wherein each blow molding station is equipped with a blow mold4and a valve block5with valves6,7for introducing or discharging blowing air9.

A compressor11for generating the blowing air9is connected through a blowing-air feed line12via a blowing-air shut-off valve14with the blowing-air inlet15aof a media distributor15for distributing the blowing air9over the individual blow molding stations2. The blowing-air exits15bof the media distributor15are each connected through blowing-air feed channels16to a control valve6for introducing the blowing air9into a blowing nozzle17provided in the valve block5. Moreover, at least one valve7and a blowing-air discharge channel18for discharging the blowing air9out of the blowing nozzle17and the blow mold, respectively, is provided on the valve block5and the blow molding station2, respectively.FIG. 1shows the blow molding machine1in a position with a valve block5lifted relative to the blow mold4, so that the blowing nozzle17is accessible from underneath.

Furthermore, the blow molding machine1comprises a CIP cleaning system20with: a processing unit22for circulating and processing a cleaning agent24; a CIP feed line26connecting an exit22aof the processing unit22via a CIP main shut-off valve28to the blowing-air feed line12and the blowing-air inlet15a, respectively, of the media distributor15; a CIP return line30which connects a CIP outlet15cof the media distributor15to an inlet22bof the processing unit22; and removable CIP sealing caps32with CIP collecting lines34for collecting and returning the cleaning agent24out of the blowing nozzles17into the CIP inlets15dof the media distributor15.

During the CIP operation the processing unit22pumps the cleaning agent24in the closed state of the blowing-air shut-off valve13and in the opened state of the CIP main shut-off valve28through the CIP feed line26, the blowing-air feed line12, the media distributor15, the blowing-air feed channels16, the valves6, the blowing nozzles17, the CIP sealing caps32, the CIP collecting lines34, the media distributor15and the CIP return line30in a circuit. The direction of flow of the cleaning agent24is symbolized inFIG. 1by arrows. The blowing-air shut-off valve13only closes the section12aof the blowing-air feed line12at the compressor side, so that neither blowing air9passes into the CIP circuit nor cleaning liquid24to the compressor11.

During the CIP operation the cleaning agent24is simultaneously pumped through the blowing-air discharge channels18and the valves7into the blowing nozzles17. Since the discharge channels18in the production process normally lead to the surrounding ambient air, these are connected in the CIP process via CIP connection lines19(plotted in broken line) to the CIP feed line26and to the media distributor15, respectively, or to the blowing-air feed line12.

FIG. 2shows the valve block5in cross section, simplified with only one pneumatically operated opened valve6for introducing the blowing air9through the blowing-air feed channel16and a connection channel35into the blowing nozzle17, for which an accommodating bore is provided in the valve block5. The valve6comprises a cylinder39with a spacer sleeve41, and a piston43with seals45,46that seal the piston43relative to the cylinder39and the spacer sleeve41, respectively.

The valve6is connected via a pneumatic control line47, a CIP shut-off valve48(each of them not shown inFIG. 1for the sake of clarity) and a conventional control or pilot valve49for opening/closing the valve6to a compressed air network that supplies compressed air51of e.g. 6 bar. In the production process the CIP shut-off valve48is opened. When the pilot valve49is opened, the compressed air51will press the piston43in the direction of the blowing-air feed channel16until it is closed. After the pilot valve49has been closed, the valve6can be opened again by the blowing air9which flows in via the blowing-air feed channel16and presses against the piston43.

In the CIP process the CIP shut-off valve48is closed to prevent the cleaning agent24from passing into the pilot valve49. Since the compressed air51is then not acting on the valve6, the cleaning agent24that flows in through the blowing-air feed channel16presses the piston43to the right side, thereby opening the valve6, and passes through the connection channel35into the blowing nozzle17.

The seals45,46prevent the cleaning agent24from penetrating into the portion39aat the control side between piston43and cylinder39—preferably entirely. However, it is also possible that the cleaning agent24that has penetrated into the portion39ais blown for completion of the CIP process after opening of the CIP shut-off valve48by the compressed air51out of the cylinder39into the blowing nozzle17. It would just as well be possible to evacuate the portion39avia a vent channel (not shown) formed in the valve block5, possibly supported by a heating of the portion39a.

The seals45,46consist of a material that is resistant to the cleaning agent24, e.g. metal, EPDM rubber, perfluoro rubber (e.g. FFKM), or a suitable material composite. Preferably, Teflon rings may also be used. The seal46that seals relative to the spacer sleeve41is here not imperatively needed.

The CIP shut-off valve48may e.g. be an electromagnetically operated shut-off valve, e.g. a cock or a bolt.

The cleaning agent24is preferably a CIP sterilizing agent, as is e.g. used for sterilizing preforms. The cleaning agent24is preferably an acid or base, such as peracetic acid, hydrogen peroxide, or soap suds. The use of alcohols is possible.

The removable CIP sealing cap32tightly ends with the valve block5and the blowing nozzle17, respectively, so that the circulating cleaning agent24can be collected completely, if possible, returned and processed. The CIP collecting line34may e.g. be a flexible line. It is decisive that for cleaning purposes the CIP sealing cap32can be mounted or removed, respectively, for the production process.

As a rule, blow molding machines operate with blowing air9of different pressure ranges, e.g. for pre-blowing, finish-blowing and inter-blowing, so that a plurality of valves6are then provided for introducing the blowing air9. These are normally opened in alternating fashion. Likewise, a plurality of bleeder valves7for discharging the blowing air9may be provided, if necessary, the valves being normally opened together. For the sake of clarityFIG. 1only shows one pressure system, e.g. that for the finishing blowing air. It goes without saying that additional valves6,7and associated lines for additional low- or high-pressure systems may be provided in the blow molding machine1according to the disclosure.

Likewise,FIG. 2only shows one valve6and the associated channels16,35in a simplifying manner. Any desired number of valves6,7with the associated channels16,35may however be provided on the valve block5. The design may also differ from the illustrated example. The relief valves7can be designed in conformity with the same operative principle as the introducing valves6. However, it goes without saying that the position of the connection channel35and of the discharge channel18may differ fromFIG. 2. For instance, the piston43could just as well close the connection channel35. It is decisive that the valves6,7and particularly the seals45,46are not attacked by the cleaning agent24and can thus be integrated into the CIP system20.

The CIP system20preferably operates in a circuit with processing of the cleaning agent24. The cleaning agent can thus be used repeatedly with a constant sterilization action so as to save resources. After having flown through the blowing nozzle17, however, the cleaning agent24could also be collected by the CIP sealing cap32and fed to a tank for disposal or separate processing.

The blow molding machine1according to the disclosure can be cleaned in the following way:

The blowing-air shut-off valve13and the CIP shut-off valves48are closed. After the CIP protection caps32have been mounted on the blowing nozzles17aand the blowing-air discharge channels18have been connected to the outlets15bof the media distributor15and the blowing-air feed line12, respectively, the CIP main shut-off valve28is opened and the processing unit22is started. Said unit pumps cleaning agent24through the blowing-air feed channels16and the blowing-air discharge channels18up to the pistons43of the valves6,7. The pistons43are displaced by the pressure of the cleaning agent24and the valves6,7are thereby opened, so that the cleaning agent24flows through the connection channels35into the blowing nozzles17. The seals45,46and the CIP shut-off valves48prevent the cleaning agent24from advancing up to the pilot valves49. The cleaning agent24is collected by the CIP sealing caps32and returned by the media distributor15and the return line30into the processing unit22. The unit regenerates the cleaning agent24and pumps it back into the CIP circuit. After a predetermined CIP flushing quantity and duration have been reached, the pumping function of the processing unit22is terminated and the CIP main shut-off valve28is closed again. Remaining cleaning agent24can now be discharged into the CIP sealing cap32and/or blown into it with blowing air9after the blowing-air shut-off valve13has been opened. In addition, after the CIP shut-off valve48has been opened, cleaning agent24passing over on the seals45,46can be blown with the control type compressed air51out of the valve cylinder39into the blowing nozzle17. The cleaning agent24that has been collected during evacuation of the feed lines12,16,18and of the media distributor15is also returned into the CIP circuit or disposed off.