Abstract:
An apparatus for shaping preforms of plastic includes a plurality of shaping stations arranged on a movable carrier. The shaping stations each have blowing molds which are arranged in blowing mold carriers and serve to accommodate the preforms of plastic. The shaping stations are conveyed within a clean chamber which is separated from its surroundings by of at least one wall. A sterilization device charges regions lying within the clean chamber with a flowable sterilization agent for sterilization thereof.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an apparatus for shaping preforms of plastic to give containers of plastic and to a process for shaping preforms of plastic to give containers of plastic. Such apparatuses and processes have been known from the prior art for a long time. In this context, for certain uses it is necessary to shape the preforms of plastic under aseptic conditions to give containers of plastic. In some countries guidelines are established for such aseptic treatments. Thus, for example, in the USA such guidelines are established and monitored by the FDA (Food and Drug Administration). 
     BACKGROUND OF THE INVENTION 
     For this purpose, the preforms of plastic are conveyed within a clean chamber and shaped to give containers of plastic during this conveying. Specifically, in this context the preforms of plastic are conveyed within blowing moulds and shaped in these blowing moulds by charging with a gaseous medium, and in particular with blowing air. WO 2010 020 529 A2 discloses such an aseptic blow moulding machine. This comprises, inter alia, a clean chamber in which the blow moulding stations or shaping stations are arranged. The subject matter of WO 200 020 529 A2 is herewith included completely in the subject matter of the present description by reference. 
     In order to establish a clean chamber atmosphere, inter alia sterilization of the internal chamber, i.e. of this clean chamber (which is also called an isolator), is necessary. In this context, this is conventionally carried out with the aid of gaseous H 2 O 2  (hydrogen peroxide) or possibly also peracetic acid. However, in this context an undesirable condensing of the H 2 O 2  on regions of the clean chamber may occur, in particular on isolator walls and installed components, such as, for example, the mould carriers. 
     The present invention is based on the object of providing a blow moulding machine which allows an improved sterilizing of the clean chamber. 
     SUMMARY OF THE INVENTION 
     An apparatus according to the invention for shaping preforms of plastic to give containers of plastic has a plurality of shaping stations which are arranged on a movable carrier, wherein the shaping stations each have blowing moulds which are arranged in blowing mould carriers and serve to accommodate the preforms of plastic and within which the preforms of plastic can be shaped to give the containers of plastic. The apparatus furthermore has a clean chamber, within which the blowing moulds or the shaping stations are conveyed or can be conveyed, wherein this clean chamber is separated from the surroundings by means of at least one wall. In addition, the apparatus also has a sterilization device which charges regions and/or components lying within the clean chamber (preferably walls and/or elements of the shaping stations) with a flowable sterilization agent for sterilization thereof. According to the invention, the regions to be sterilized can be heated at least in part. 
     It is therefore proposed that certain or several of the regions to be sterilized are heated in order to facilitate the sterilization. The heating of these regions is therefore advantageously carried out precisely for the purpose of sterilization. Advantageously, the regions are heated to at least 50°, especially if hydrogen peroxide (H 2 O 2 ) is used, since this temperature lies above the dew point of this substance. The use of these temperatures therefore helps to prevent condensing of the H 2 O 2 , for example on the isolator walls and the installed components. 
     The heated regions can be, for example, walls which form the boundary of the clean chamber. In addition, however, they can also be other regions or elements which are within the clean chamber, such as, for example, blowing moulds or elements thereof, blowing mould carriers, carrier trays, blow moulding dies, stretching rods and the like. 
     In a further advantageous embodiment, the sterilization device is arranged inside the clean chamber. In this context it is possible for the sterilization device to be constructed, for example, as a charging device, such as, for example, as a die, which charges the particular regions of the clean chamber, such as the internal walls or also the mould carriers, with the sterilization agent. In this context, the charging device can be arranged, for example, in a stationary manner, and in particular can charge the parts of the clean chamber which are movable relative to the charging devices. It would also be possible for the sterilization device to be arranged in a movable manner, in order in particular to charge the regions of the clean chamber which are arranged in a stationary manner with the sterilization agent. In a further advantageous embodiment, a plurality of such charging devices, which together form the said sterilization device, is arranged inside the clean chamber. Advantageously, a reservoir is provided, which supplies the sterilization device with sterilization agent, and this reservoir is particularly preferably arranged outside the clean chamber. 
     In a further advantageous embodiment, at least two of the walls which form the boundary of the clean chamber are movable relative to one another. It is thus possible for an external wall to be of a standing configuration and for the internal wall to be formed, for example, by the carrier or the blow moulding wheel and to move. In this context, sealing devices, such as, for example, water locks, can be arranged between the wall which are movable relative to one another. 
     In this context, the walls in particular which belong to the carriers or the blow moulding wheel are advantageously to be heated. This is based on the fact that these carriers have a very high mass and heating is therefore particularly significant. 
     Advantageously, at least one of the walls forming the boundary of the clean chamber is formed by the carrier or a region of the carrier, for example the carrier can have a C-shaped structure with an upper and lower flange, at least one of these walls being heated. Advantageously, at least two walls of the clean chamber and particularly preferably at least three walls of the clean chamber are formed by the carrier. In a further advantageous embodiment, all the movable walls of the clean chamber are formed by the carrier. In this context, these walls can form a circulating recess in which the particular shaping stations are arranged. 
     In a further advantageous embodiment, the apparatus has an electrically operated heating device for heating the regions. Thus, for example, heating mats or heating wires which heat parts of the walls, for example those walls which are formed by the carrier, can be arranged in the apparatus. In particular, such heating devices can be arranged on a side of the blow moulding wheel or carrier facing away from the clean chamber. This prevents the components being heated from having themselves to be arranged in the clean chamber. In a further advantageous embodiment, the apparatus has feed devices in order to blow a heated medium, such as, for example, hot air, into the clean chamber. In this context, this blowing in of heated air can take place before the sterilization operation. The carrier is advantageously a rotatable carrier, which is also called a blow moulding wheel in the following. 
     A problem in the context of the sterilization is the high mass of this blow moulding wheel, which makes rapid heating up difficult. An appropriately massive construction of the blow moulding wheel is advantageous, however, since it must mount the mould carriers reliably and without tolerances, and this in particular also on application of a blowing pressure of up to 40 bar. It is thus possible, for example, to install electrical heating devices, such as heating mats, on the blow moulding wheel (and there advantageously on the side facing away from the clean chamber). These accelerate the heating of the blow moulding wheel. However, it would also be possible to provide a steam-operated heating device. 
     In a further advantageous embodiment, bores for carrying a temperature control medium are provided in the carrier or on one of the other walls and/or on constituents of the shaping stations. In this case a heating medium (e.g. steam) can be passed through the bores in the carrier or blow moulding wheel. Heating up of the carrier to the required temperature can also be accelerated by this means. Advantageously, both a region of the carrier is heated and heated air is introduced into the clean chamber. 
     However, other procedures for the heating are also conceivable. Primary energy could thus be used for the heating, or the waste air from an oven upstream of the blow moulding machine could be used for the heating. This heated air from the oven could be used to charge the blow moulding wheel from the outside for heating thereof. In addition, the heated air could also be used using the ventilation system (which is in any case present) in order to heat the clean chamber from the inside or outside. In this context, sterile filters could also be used in a feed line of the heated air. In addition, a cooling device, which cools constituents such as e.g. a blowing mould base during operation, could also be used to heat these components before or during a sterilization operation. 
     In a further advantageous embodiment, the carrier has a base body and, on a surface facing the clean chamber, a temperature control body arranged in a predetermined position with respect to the base body. As mentioned above, hot air is advantageously blown into the clean chamber via the ventilation system before the sterilization. The intention of this is to ensure that all the components in the isolator are heated up to the required temperature. Since this, as mentioned, is difficult in the case of the carrier or blow moulding wheel because of the massive construction thereof, in the context of this embodiment it is proposed that the blow moulding wheel is designed in a sandwich construction. 
     In this context, the base body or the base structure can continue to be massive in construction. However, a further layer (i.e. the temperature control body) is added inside, i.e. there where the clean chamber is located. In this context, this can be, for example, a further sheet metal layer of considerably lower wall thickness. Advantageously, an insulating medium is formed or an insulating medium (in particular for thermal insulation) is arranged between the base body and the temperature control body. Thus, for example, an air cushion which has an insulating effect can be formed between the base body and the temperature control body. This temperature control medium or the thin sheet metal layer can be heated relatively rapidly. The base body and the temperature control body are therefore advantageously at a distance from one another. 
     Instead of the air cushion, however, one or more layers of insulating material could also be employed between the base body and the temperature control body. With this additional temperature control body it is no longer necessary to produce the entire blow moulding wheel from a special material, such as, for example, Niro. Less expensive structural steel can be used. However, the temperature control body is advantageously made of a material which can be easily heated, such as, for example, of Niro. 
     In a further advantageous embodiment, the mould carriers holding the blowing moulds also have bores for carrying a temperature control medium, and in particular for carrying a temperature control medium for heating the mould carriers. Advantageously, the mould carriers also have (or the apparatus also has) a feed device in order to feed a heated temperature control medium to these bores. A reservoir for the temperature control medium is advantageously arranged outside the clean chamber. 
     In this context it would be possible, for example, to employ the cooling bores which cool the blowing moulds during the production operation. These cooling bores often have hoses, pipes and the like leading outwards, in order to be able to feed in and remove the cooling media. This cooling apparatus can be used during the sterilization operation in order to heat the mould carriers. 
     The present invention furthermore relates to a process for shaping preforms of plastic to give containers of plastic, wherein the preforms of plastic are conveyed with a plurality of shaping stations, which are arranged on a movable carrier, and the preforms of plastic are arranged in blowing moulds in order to be expanded there to give the containers of plastic. In this context, the shaping stations are conveyed within a clean chamber, which clean chamber is separated off from the surroundings by means of at least one wall. Furthermore, during the sterilization operation regions of the apparatus which are arranged within the clean chamber are charged with a flowable sterilization medium by a sterilization device. 
     According to the invention, at least sections of regions to be sterilized are heated. Advantageously, in this context the regions to be sterilized are heated for the purpose of this sterilization. In this context, this heating can take place before and/or also during the sterilization operation. 
     With respect to the process, it is therefore also proposed to heat parts of the clean chamber or also of the shaping stations before the sterilization and in particular for the purpose of the sterilization. 
     In a preferred process, the regions are heated to a temperature which is greater than 40° C., preferably greater than 45° C. and particularly preferably greater than 50° C. 
     Preferably, the regions are heated to the temperature which lies above the dew point of the particular sterilization agent used. 
     In a further advantageous process, the heating is carried out electrically and/or by a flowable temperature control medium. 
     Further advantages and embodiment can be seen from the attached drawings. In these: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a diagrammatic representation of an installation for production of containers of plastic; 
         FIG. 2  shows a view of a clean chamber in the region of a shaping station; 
         FIG. 3  shows a detailed representation of an apparatus according to the invention in a first embodiment; 
         FIG. 4  shows a detailed representation of the apparatus in a second embodiment; and 
         FIG. 5  shows a further detailed representation of a device according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a diagrammatic representation of an installation for production of containers of plastic. This installation  50  has a heating device  30  in which preforms of plastic  10  are heated. These preforms of plastic  10  here are led by means of a conveying device  34 , such as here a circulating chain, through this heating device  30  and are thereby heated with a plurality of heating elements  31 . This heating device  30  is followed by a transfer unit  36  which transfers the preforms  10  to a sterilization device  32 . This sterilization device  32  here likewise has a conveying wheel  37  and sterilization elements can be arranged on this conveying wheel  37 , or also in a stationary manner. In this region, for example, sterilization by hydrogen peroxide gas or also by electromagnetic or UV radiation is possible. In particular, an internal sterilization of the preforms is carried out in this region. 
     Reference symbol  20  designates a clean chamber in its entirety, the outer boundaries of which are indicated here by the dotted line L. In a further preferred embodiment the clean chamber  20  is arranged not only in the region of the conveying wheel  2  and filling device  40 , but possibly already starts in the region of the heating device  30 , the sterilization device  32 , the feed line of the preforms of plastic and/or the production of the preforms of plastic. It can be seen that this clean chamber  20  starts in the region of the sterilization unit  32 . Lock devices can be provided in this region in order to introduce the preforms of plastic into the clean chamber  20  without too much gas thereby flowing within the clean chamber and being lost in this way. 
     As indicated by the broken line L, the clean chamber is adapted to the outer shape of the individual components of the installation. The volume of the clean chamber can be reduced in this manner. 
     Reference symbol  1  designates a shaping apparatus in its entirety, in which a plurality of blow moulding stations or shaping stations  8  is arranged on a conveying wheel  2 , only one of these blow moulding stations  8  being shown here. The preforms of plastic  10  are expanded into containers  10   a  with these blow moulding stations  8 . Although not shown here in detail, the entire region of the conveying device  2  is not within the clean chamber  20 , but the clean chamber  20  or isolator is realized to a certain extent as a mini-isolator within the entire apparatus. It would thus be possible for the clean chamber to be of channel-like construction at least in the region of the shaping apparatus  1 . 
     Reference symbol  22  refers to a feed device which transfers the preforms to the shaping device  1 , and reference symbol  24  refers to a removal device which removes the containers of plastic  10   a  produced from the shaping apparatus  1 . It can be seen that the clean chamber  20  has recesses in each case in the region of the feed device  22  and the removal device  24 , which accommodate these devices  22 ,  24 . In this manner, a transfer of the preforms of plastic  10  to the shaping apparatus  1  or a taking over of the containers of plastic  10   a  from the shaping apparatus  1  can be achieved in a particularly advantageous manner. 
     The expanded containers of plastic are transferred to a filling device  40  with a transfer unit  42 , and are then removed from this filling device  40  via a further conveying unit  44 . The filling device  40  here is also within the said clean chamber  20 . In the case of the filling device also, it would be possible for the entire filling device  40  with, for example, a reservoir for a drink not to be arranged completely within the clean chamber  20 , but here also only those regions in which the containers are actually led. In this respect, the filling device could also be constructed in a similar manner to the apparatus  1  for shaping preforms of plastic  10 . 
     As mentioned, the clean chamber  20  is reduced to a smallest possible region in the region of the apparatus  1 , namely essentially to the blow moulding stations  8  themselves. Due to this small construction design of the clean chamber  20  it is possible for a clean chamber to be produced altogether more easily and faster, and maintaining sterile conditions in the operating phase requires less outlay. Also, less sterile air is needed, which leads to smaller filter installations and the risk of uncontrolled eddy formation is also reduced. 
       FIG. 2  shows a detailed representation of the apparatus  1  in the region of a blow moulding station  8 . A plurality of such blow moulding stations  8  is moved in rotation around an axis X with a conveying device  2  or a carrier. The blow moulding station  8 , as can be seen in  FIG. 2 , is led within the clean chamber  20 , which is of channel-like construction here. This clean chamber  20  is closed off by a movable side wall  19  and a cover  17  constructed as one part with this side wall  19 . This side wall  19  and the cover  17  here rotate together with the blow moulding station  8 . 
     Reference symbol  18  refers to a further wall which forms the boundary of the clean chamber  20 . This wall  18  here is an outside wall which is arranged in a stationary manner. Between the cover  17  and the wall  18  a sealing device  25  is provided, which seals off from one another the elements  17  and  18  which are movable relative to one another, for example, as mentioned above, using a water lock. The lower region of the wall  18  is arranged in a fixed and sealed-off manner on a base  13 . Within the clean chamber  20  and here directly adjoining the wall  19  a carrier  76  is provided, which likewise moves in rotation and on which in turn a holding device  23  which holds the blow moulding station  8  is provided. 
     Reference symbol  11  refers to a secondary device which can be actuated by a guide curve  9  in order to open and to close the blow moulding station on its path through the clean chamber  20 , in order in particular to insert the preform of plastic into the blow moulding station and in order also to remove it again. A guide curve  9  here is also arranged within the clean chamber  20 . However, it would also be possible, for example, for just a section  11  already to lead out of the clean chamber  20  below the individual blow moulding stations  8 . 
     The conveying device  2  can have still further elements which are arranged above the clean chamber  20 . 
     The carrier  26  here is arranged in a fixed manner on a holding body  29 , and this holding body in turn is movable relative to the base  13 . Reference symbol  27  here refers to a further sealing device which also effects, in this region, sealing of the regions  13  and  29  which are movable relative to one another. 
     Reference symbol  5  refers to a stretching rod which is movable relative to the blow moulding station, in order to stretch the preforms of plastic  10  in their longitudinal direction. A slide  12  here, relative to which the stretching rod is movable in the direction Y, is arranged on the cover  17  here. Reference symbol  21  refers to a further holding means for this slide  12  of the stretching rod  5 . 
     It can be seen that certain regions of the stretching rod are both outside the clean chamber  20  and within the clean chamber  20  during the blow moulding operation. For this purpose, it is possible for a protective device, such as a folding bellows, which surrounds the stretching rod  5  to be provided outside the clean chamber  20  or above the slide  12 , so that no region of the stretching rod  5  comes directly into contact with the outside surroundings. Reference symbol U identifies the (non-sterile) surroundings of the clean chamber  20 . Reference symbol  28  identifies a carrier for carrying a base form, which is likewise a constituent of the blowing mould. This carrier likewise can be moved here in the direction Y. 
     Reference symbol  55  refers to a sterilization device, which here is preferably arranged inside the clean chamber  20  and serves to sterilize the individual shaping stations or constituents of these shaping stations  8 . This sterilization device  55  here can charge the shaping stations  8 , for example, with hydrogen peroxide or another sterilization agent. The sterilization device  55  here can be arranged in a stationary manner, and the shaping stations can move relative to this sterilization device  55 . This sterilization device or charging device  55  can be on the conveying wheel  2  or on the standing wall  18  or can be generally arranged in a stationary manner and can comprise dies or the like. It is furthermore advantageous to introduce sterile air via the ventilation system into the clean chamber  20  for sterilizing the clean chamber  20 . 
     The blowing moulds (not shown) are arranged within the blowing mould carrier  6 . More precisely, two blowing mould carrier parts which are swivellable relative to one another and which each hold a blowing mould part can be arranged here. By this swiveling operation, the blowing moulds can be opened for introduction of preforms of plastic and for removal of finished blow moulded containers. These blowing mould carriers and blowing moulds here are likewise arranged within the clean chamber. 
     However, it would also be possible (differently to that shown in  FIG. 2 ) and preferable for the conveying device  2  or the carrier to have a C-shaped outer circumference, which also partly forms the external walls of the clean chamber. This C-shaped clean chamber wall therefore rotates here with the conveying device  2 , i.e. the blow moulding wheel. In this embodiment the lower boundary of the clean chamber is at a distance from the base  13  and moves relative to the base. In this manner, the clean chamber can be even smaller in design than shown in  FIG. 2 . Sealing off of this C-shaped profile of the conveying device, which here forms both an internal wall and a lower and upper cover for the clean chamber, preferably takes place here only with respect to the external wall of the clean chamber. This external wall here is advantageously arranged in a stationary manner. 
       FIG. 3  shows a partial representation of an apparatus  1  according to the invention. The carrier  2 , within which a clean chamber  20  is formed, can be seen in turn here, this clean chamber  20  being of a channel-like design. A plurality (only one shown) of blowing moulds  4  is arranged within the carrier, each of which are held on carriers  6 . More precisely, only one blowing mould part  4 , which is arranged on a blowing mould carrier part, is shown in  FIG. 3 . A corresponding second blowing mould part and a corresponding carrier part are not shown in  FIG. 3 . The blowing mould carrier  6  is arranged here on a swivellable shaft  58 . The end sections  58   a  and  58   b  of this shaft project out of the sterile chamber  20  here through the cover  17  and the base  52 . Actuation of the swiveling shaft  58  from the outside, i.e. from outside the clean chamber  20 , is possible in this manner. 
     The cover  17  and the base  52  are constructed here as one part with the wall  19 . These three walls are each a constituent of the carrier designated in its entirety with 2. It can be seen that the swiveling shaft  58  is arranged on the wall  17  and  52 . For this reason these walls must likewise be very massive in construction. During operation, the walls  17 ,  19  and  52  move and in contrast the external wall  18  is arranged in a standing manner. It would be conceivable for the external wall  18  to be less stable or massive in construction than the further walls  17 ,  19  and  52 , since this external wall  18  is not subjected to such high forces. Reference symbol  25  again identifies the sealing device in order to seal off the movement of the standing wall  18  relative to the movable wall  52 . A corresponding sealing device can also be provided for sealing off the standing wall  18  from the cover  17 . 
     Since, as mentioned, the walls  17 ,  19 ,  52  are each constituents of the carrier  2  and are to be very massive in construction, it is now proposed that these walls are temperature-controlled before the charging with a sterilization medium. This temperature control here can be carried out in various ways. Thus, for example, a heating device  72  can be arranged on the inside, i.e. the side of the wall  19  facing the axis of rotation (and facing away from the clean chamber  20 ), in order to heat the carrier or the wall  19  in this manner. Corresponding heating devices could also be arranged on the cover  17  or under the base  52 . 
     Reference symbol  54  identifies an opening arranged in the cover, for example in order to introduce a stretching rod into the particular blowing moulds, or in order to guide a blow moulding die to the preforms of plastic. Reference symbol  56  identifies an opening in the base  52 , for example in order also to provide the blowing mould  4  with a base part (not shown), which adjoins the blowing mould parts or can be removed from these. The drives for this base form and preferably also for the stretching rod and/or a blow moulding die here can be outside the clean chamber  20 . It would furthermore be possible to seal off these components, for example by means of folding bellows and the like. 
       FIG. 4  shows an embodiment for achieving heating. In this, bores  62  for a temperature control medium are arranged in the carrier  2  or the side wall  19 . A temperature control medium for temperature control of the wall  19 , for example warm or hot oil or also water, can be sent through these bores in order to heat the carrier  2 , more precisely the walls  19 ,  17  and  52 , in this manner. Corresponding temperature control medium bores could also be arranged in the regions  17  and  52 . Continuous bores which extend through all three walls  17 ,  19  and  52  could also be provided. 
       FIG. 5  shows a further embodiment of an apparatus according to the invention. In this, the carrier  2  has a base body  2   a  and a temperature control device  64 , which can be constructed, for example, as a thin wall of sheet metal. An air gap  66  can be formed between the base body  2   a  and this temperature control body  64 , which effects insulation between the temperature control body  64  and the base body  2   a . Air, for example, or also a further insulating medium can be arranged in this region or gap  66 . It is possible in this manner to charge the temperature control body  64  with heat, for example with hot steam, in a relatively short time without the base body  2   a  also thereby having to be heated at the same time. It can be seen that the temperature control body  64  also extends below the cover  17  and a corresponding gap  66  is also formed here. It would also be possible also to arrange the temperature control body in the region of the base  52  and thereby here also to provide again a corresponding insulating space  66 . 
     The applicant reserves the right to claim all the features disclosed in the application text as essential to the invention where they are, individually or in combination, novel with respect to the prior art. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Device 
           2  Carrier 
           2   a  Base body 
           4  Blowing mould 
           6  Blowing mould carrier 
           9  Guide curve 
           10  Preforms of plastic 
           10   a  Container 
           11  Secondary device 
           12  Slide 
           13  Base 
           17  Cover 
           18  Wall 
           19  Side wall, section 
           20  Clean chamber 
           22  Feed device 
           23  Holding device 
           24  Removal device 
           25  Sealing device 
           26  Carrier 
           27  Sealing device 
           28  Carrier (for base form) 
           29  Holding body 
           30  Heating device 
           31  Heating elements 
           32  Sterilization device 
           34  Conveying device 
           36  Transfer unit 
           37  Conveying wheel 
           40  Filling device 
           42  Transfer unit 
           44  Conveying unit 
           50  Arrangement 
           52  Base, wall 
           54 ,  56  Opening 
           55  Sterilization device 
           58  Shaft 
           58   a ,  58   b  End sections 
           62  Bores 
           64  Temperature control device 
           66  Gap, insulating space 
           72  Heating device 
         X Axis 
         Y Direction 
         U Surroundings