Abstract:
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.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    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 
       [0002]    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 
       [0003]    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 Ul, 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. 
         [0004]    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 
       [0005]    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. 
         [0006]    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. 
         [0007]    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. 
         [0008]    Preferably, the valves must be operated pneumatically. The blow molding machine can thus be controlled in a reliable and inexpensive way. 
         [0009]    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. 
         [0010]    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. 
         [0011]    Control valves are conventionally also called pilot valves. 
         [0012]    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. 
         [0013]    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. 
         [0014]    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. 
         [0015]    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. 
         [0016]    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. 
         [0017]    Preferably, the CLP 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. 
         [0018]    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. 
         [0019]    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. 
         [0020]    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. 
         [0021]    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. 
         [0022]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    A preferred embodiment of the blow molding machine according to the disclosure is shown in the drawing, in which: 
           [0024]      FIG. 1  is a schematic illustration of a blow molding machine according to the disclosure with CIP system; 
           [0025]      FIG. 2  is a schematic cross-section through a valve block with a pneumatically controlled valve for introducing blowing air. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0026]    As can be seen in  FIG. 1 , the blow molding machine  1  is configured in the embodiment in the known way as a rotary machine with a plurality of blow molding stations  2  arranged in symmetry around a rotational axis  1 ′ and used for producing plastic bottles  3 , wherein each blow molding station is equipped with a blow mold  4  and a valve block  5  with valves  6 ,  7  for introducing or discharging blowing air  9 . 
         [0027]    A compressor  11  for generating the blowing air  9  is connected through a blowing-air feed line  12  via a blowing-air shut-off valve  14  with the blowing-air inlet  15   a  of a media distributor  15  for distributing the blowing air  9  over the individual blow molding stations  2 . The blowing-air exits  15   b  of the media distributor  15  are each connected through blowing-air feed channels  16  to a control valve  6  for introducing the blowing air  9  into a blowing nozzle  17  provided in the valve block  5 . Moreover, at least one valve  7  and a blowing-air discharge channel  18  for discharging the blowing air  9  out of the blowing nozzle  17  and the blow mold, respectively, is provided on the valve block  5  and the blow molding station  2 , respectively.  FIG. 1  shows the blow molding machine  1  in a position with a valve block  5  lifted relative to the blow mold  4 , so that the blowing nozzle  17  is accessible from underneath. 
         [0028]    Furthermore, the blow molding machine  1  comprises a CIP cleaning system  20  with: a processing unit  22  for circulating and processing a cleaning agent  24 ; a CIP feed line  26  connecting an exit  22   a  of the processing unit  22  via a CIP main shut-off valve  28  to the blowing-air feed line  12  and the blowing-air inlet  15   a , respectively, of the media distributor  15 ; a CIP return line  30  which connects a CIP outlet  15   c  of the media distributor  15  to an inlet  22   b  of the processing unit  22 ; and removable CIP sealing caps  32  with CIP collecting lines  34  for collecting and returning the cleaning agent  24  out of the blowing nozzles  17  into the CIP inlets  15   d  of the media distributor  15 . 
         [0029]    During the CIP operation the processing unit  22  pumps the cleaning agent  24  in the closed state of the blowing-air shut-off valve  13  and in the opened state of the CIP main shut-off valve  28  through the CIP feed line  26 , the blowing-air feed line  12 , the media distributor  15 , the blowing-air feed channels  16 , the valves  6 , the blowing nozzles  17 , the CIP sealing caps  32 , the CIP collecting lines  34 , the media distributor  15  and the CIP return line  30  in a circuit. The direction of flow of the cleaning agent  24  is symbolized in  FIG. 1  by arrows. The blowing-air shut-off valve  13  only closes the section  12   a  of the blowing-air feed line  12  at the compressor side, so that neither blowing air  9  passes into the CIP circuit nor cleaning liquid  24  to the compressor  11 . 
         [0030]    During the CIP operation the cleaning agent  24  is simultaneously pumped through the blowing-air discharge channels  18  and the valves  7  into the blowing nozzles  17 . Since the discharge channels  18  in the production process normally lead to the surrounding ambient air, these are connected in the CIP process via CIP connection lines  19  (plotted in broken line) to the CIP feed line  26  and to the media distributor  15 , respectively, or to the blowing-air feed line  12 . 
         [0031]      FIG. 2  shows the valve block  5  in cross section, simplified with only one pneumatically operated opened valve  6  for introducing the blowing air  9  through the blowing-air feed channel  16  and a connection channel  35  into the blowing nozzle  17 , for which an accommodating bore is provided in the valve block  5 . The valve  6  comprises a cylinder  39  with a spacer sleeve  41 , and a piston  43  with seals  45 ,  46  that seal the piston  43  relative to the cylinder  39  and the spacer sleeve  41 , respectively. 
         [0032]    The valve  6  is connected via a pneumatic control line  47 , a CIP shut-off valve  48  (each of them not shown in  FIG. 1  for the sake of clarity) and a conventional control or pilot valve  49  for opening/closing the valve  6  to a compressed air network that supplies compressed air  51  of e.g. 6 bar. In the production process the CIP shut-off valve  48  is opened. When the pilot valve  49  is opened, the compressed air  51  will press the piston  43  in the direction of the blowing-air feed channel  16  until it is closed. After the pilot valve  49  has been closed, the valve  6  can be opened again by the blowing air  9  which flows in via the blowing-air feed channel  16  and presses against the piston  43 . 
         [0033]    In the CIP process the CIP shut-off valve  48  is closed to prevent the cleaning agent  24  from passing into the pilot valve  49 . Since the compressed air  51  is then not acting on the valve  6 , the cleaning agent  24  that flows in through the blowing-air feed channel  16  presses the piston  43  to the right side, thereby opening the valve  6 , and passes through the connection channel  35  into the blowing nozzle  17 . 
         [0034]    The seals  45 ,  46  prevent the cleaning agent  24  from penetrating into the portion  39   a  at the control side between piston  43  and cylinder  39 —preferably entirely. However, it is also possible that the cleaning agent  24  that has penetrated into the portion  39   a  is blown for completion of the CIP process after opening of the CIP shut-off valve  48  by the compressed air  51  out of the cylinder  39  into the blowing nozzle  17 . It would just as well be possible to evacuate the portion  39   a  via a vent channel (not shown) formed in the valve block  5 , possibly supported by a heating of the portion  39   a.    
         [0035]    The seals  45 ,  46  consist of a material that is resistant to the cleaning agent  24 , e.g. metal, EPDM rubber, perfluoro rubber (e.g. FFKM), or a suitable material composite. Preferably, Teflon rings may also be used. The seal  46  that seals relative to the spacer sleeve  41  is here not imperatively needed. 
         [0036]    The CIP shut-off valve  48  may e.g. be an electromagnetically operated shut-off valve, e.g. a cock or a bolt. 
         [0037]    The cleaning agent  24  is preferably a CIP sterilizing agent, as is e.g. used for sterilizing preforms. The cleaning agent  24  is preferably an acid or base, such as peracetic acid, hydrogen peroxide, or soap suds. The use of alcohols is possible. 
         [0038]    The removable CIP sealing cap  32  tightly ends with the valve block  5  and the blowing nozzle  17 , respectively, so that the circulating cleaning agent  24  can be collected completely, if possible, returned and processed. The CIP collecting line  34  may e.g. be a flexible line. It is decisive that for cleaning purposes the CIP sealing cap  32  can be mounted or removed, respectively, for the production process. 
         [0039]    As a rule, blow molding machines operate with blowing air  9  of different pressure ranges, e.g. for pre-blowing, finish-blowing and inter-blowing, so that a plurality of valves  6  are then provided for introducing the blowing air  9 . These are normally opened in alternating fashion. Likewise, a plurality of bleeder valves  7  for discharging the blowing air  9  may be provided, if necessary, the valves being normally opened together. For the sake of clarity  FIG. 1  only shows one pressure system, e.g. that for the finishing blowing air. It goes without saying that additional valves  6 ,  7  and associated lines for additional low- or high-pressure systems may be provided in the blow molding machine  1  according to the disclosure. 
         [0040]    Likewise,  FIG. 2  only shows one valve  6  and the associated channels  16 ,  35  in a simplifying manner. Any desired number of valves  6 ,  7  with the associated channels  16 ,  35  may however be provided on the valve block  5 . The design may also differ from the illustrated example. The relief valves  7  can be designed in conformity with the same operative principle as the introducing valves  6 . However, it goes without saying that the position of the connection channel  35  and of the discharge channel  18  may differ from  FIG. 2 . For instance, the piston  43  could just as well close the connection channel  35 . It is decisive that the valves  6 ,  7  and particularly the seals  45 ,  46  are not attacked by the cleaning agent  24  and can thus be integrated into the CIP system  20 . 
         [0041]    The CIP system  20  preferably operates in a circuit with processing of the cleaning agent  24 . The cleaning agent can thus be used repeatedly with a constant sterilization action so as to save resources. After having flown through the blowing nozzle  17 , however, the cleaning agent  24  could also be collected by the CIP sealing cap  32  and fed to a tank for disposal or separate processing. 
         [0042]    The blow molding machine  1  according to the disclosure can be cleaned in the following way: 
         [0043]    The blowing-air shut-off valve  13  and the CIP shut-off valves  48  are closed. After the CIP protection caps  32  have been mounted on the blowing nozzles  17   a  and the blowing-air discharge channels  18  have been connected to the outlets  15   b  of the media distributor  15  and the blowing-air feed line  12 , respectively, the CIP main shut-off valve  28  is opened and the processing unit  22  is started. Said unit pumps cleaning agent  24  through the blowing-air feed channels  16  and the blowing-air discharge channels  18  up to the pistons  43  of the valves  6 ,  7 . The pistons  43  are displaced by the pressure of the cleaning agent  24  and the valves  6 ,  7  are thereby opened, so that the cleaning agent  24  flows through the connection channels  35  into the blowing nozzles  17 . The seals  45 ,  46  and the CIP shut-off valves  48  prevent the cleaning agent  24  from advancing up to the pilot valves  49 . The cleaning agent  24  is collected by the CIP sealing caps  32  and returned by the media distributor  15  and the return line  30  into the processing unit  22 . The unit regenerates the cleaning agent  24  and pumps it back into the CIP circuit. After a predetermined CIP flushing quantity and duration have been reached, the pumping function of the processing unit  22  is terminated and the CIP main shut-off valve  28  is closed again. Remaining cleaning agent  24  can now be discharged into the CIP sealing cap  32  and/or blown into it with blowing air  9  after the blowing-air shut-off valve  13  has been opened. In addition, after the CIP shut-off valve  48  has been opened, cleaning agent  24  passing over on the seals  45 ,  46  can be blown with the control type compressed air  51  out of the valve cylinder  39  into the blowing nozzle  17 . The cleaning agent  24  that has been collected during evacuation of the feed lines  12 ,  16 ,  18  and of the media distributor  15  is also returned into the CIP circuit or disposed off.