DE102012025788B3 - Device and method for expanding plastic containers - Google Patents

Abstract

Device (1) for expanding plastic containers (10) with a transport device (14), which transports the plastic containers (10) along a predetermined transport path, with at least a first forming station arranged on the transport device (14) and transported by the transport device (14). (4), which expands the plastic containers (10) by applying a gaseous medium, with at least a second forming station (6) arranged on the transport device (14) and transported by the transport device (14), which expands the plastic containers by applying a gaseous medium expands, wherein the first forming station (4) and the second forming station (6) each have stretching rods (12) for stretching the plastic containers (10) to be expanded in their longitudinal directions and these stretching rods each have a channel through which the plastic containers (10) to be expanded are passed ) a gaseous medium can be supplied through the stretch rod (12) and with at least one first gas supply device (22), which at least temporarily provides the first forming station (4) with a pressurized gaseous medium, this gaseous medium being in the first Forming station (4) to expand plastic containers (10) can be fed at least temporarily through the stretching rod (12), characterized in that the device (1) has a second gas supply device (24) which has an interior of the in the first forming station (4) The plastic container (10) to be expanded is in flow connection in such a way that a gas flowing between the second gas supply device (24) and the interior of the plastic container (10) flows between the stretching rod (12) and a wall of the plastic container (10), the first gas supply device (22) and the second gas supply device (24) are at least temporarily in flow connection via the interior of the plastic container (10) arranged in the first forming station (4), and this second gas supply device (24) is also in flow connection with one in the second forming station (6). located plastic container (10), and wherein the pressure conditions of the first gas supply device (22) and the second gas supply device (24) are selected such that at least temporarily a gas flow takes place from the second gas supply device (24) to the first gas supply device (22), whereby a valve (P2) for the second gas supply device (24) and a valve (BK) for the first gas supply device (22) are each kept open during the stabilization of the container (10), wherein in at least one period of time the stretch rod (12) flowing air is used for cooling and at the same time is made available at least indirectly to a further forming station (4), and the blown air is guided by a compressor into the first gas supply device (22) and from there through the rinsing or stretching rod (12). Already fully formed containers are directed to the second gas supply device (24) in the printing and cooling phase, so that the blown air for pre- and final blowing does not come directly from a compressor, but is redirected.

Description

The present invention relates to a device and a method for producing plastic containers and in particular for forming plastic preforms into plastic containers. Such devices and methods are from the prior art, among other things, from the publications DE 10 2004 014 653 A1 and DE 600 15 577 T2 known for a long time. Usually, plastic preforms are first heated using an oven and then these heated plastic preforms are formed into the containers in a blow molding machine, in particular a stretch blow molding machine, by applying blown air. This forming process is a relatively complex process and is usually divided into several steps. The container is expanded with a pre-blow pressure, then a finished blow pressure is usually applied and finally the container expanded in this way is kept under this pressure for a predetermined time so that the deformed state can stabilize.

Devices and methods are also known from the prior art in which the containers are partially cooled during the forming process or afterwards, in particular in a bottom area, in order to stabilize the bottom area in this way. Furthermore, other approaches are also known for achieving this ground stability. It is known that base cooling using air or water variants is installed in the outlet of such a blow molding machine. However, such after-cooling comes with various disadvantages. With air fan cooling, the ideal conditions can only be achieved in the rarest of cases. For example, in the case of a vortex nozzle, unnecessary air consumption occurs. Even with a fan variant, ideal installation conditions are rarely present. Post-cooling the bottom using water has the disadvantage that the containers are then moistened or wetted with water, which in turn poses a problem for subsequent labeling.

The present invention is therefore based on the object of providing a device and a method which make container production more energy efficient. In particular, a device and a method should also be made possible which enables certain container areas, in particular a base, to be cooled during blow molding.

This object is achieved according to the invention by the subjects of independent claims 1, 2 and 15. Advantageous embodiments and further developments are the subject of the subclaims.

A device according to the invention for expanding plastic containers has a transport device which transports the plastic containers along a predetermined transport path. Furthermore, the device has at least one first forming station arranged on the transport device and transported by the transport device, which expands the plastic containers by applying a gaseous medium (or in which the plastic preforms are expanded). In addition or in addition, it is also possible for the plastic containers to be cooled by passing a gaseous medium through them. Furthermore, a second forming station arranged on the transport device and transported by the transport device is provided, which expands the plastic containers by applying a gaseous medium. Furthermore, the first forming station and second forming station each have stretching rods for stretching the plastic containers to be expanded in their longitudinal directions and these stretching rods each have a channel via which a gaseous medium can be fed to the plastic containers to be expanded through the stretching rod.

Furthermore, the device has a first gas supply device, which at least temporarily provides the first forming station with a pressurized gaseous medium, this gaseous medium being able to be fed at least temporarily through the stretching rod to this plastic container to be expanded in the first forming station. It is possible for the first gas supply device to make the pressurized gaseous medium available to the first forming station for expanding a plastic container to be expanded in the second forming station and/or for maintaining an expansion state of this plastic container and/or for cooling the plastic container. The term expanding the container is also understood below to mean the entire process including any stabilization and cooling phases.

According to the invention, the device has a second gas supply device, which can be brought into flow connection with an interior of the plastic container to be expanded in the first forming station in such a way that a gas flowing between the second gas supply device and the interior of the plastic container flows between the stretching rod and a wall of the plastic container, wherein the first gas supply device and the second gas supply device are at least temporarily in flow connection via the interior of the plastic container arranged in the first forming station and this second gas supply device is also at least temporarily in flow connection with a plastic container located in the second forming station and wherein the pressure conditions of the first gas supply device and the second gas supply device are selected such that at least temporarily a gas flow from the second gas supply device to the first gas supply device - in particular via the plastic container located in the first forming station - takes place.

It would also be conceivable that individual devices do not use stretching rods that stretch the containers, but instead use rinsing rods that are guided into the interior of the containers in order to cool the interior of the container, in particular its bottom or side walls, but then do not necessarily carry out a stretching process of the containers. The stretch rods are particularly preferably rinsing rods, which make it possible to rinse or cool the container by supplying a medium.

The second gas supply device preferably serves to apply gas to the container in such a way that its internal volume increases. The second gas supply device is therefore preferably responsible for increasing the volume of the plastic container (located in particular within a blow mold). The second gas supply device therefore preferably provides the pressure for carrying out the final blowing process.

According to the invention, a device is therefore proposed in which at least two gas supply devices are available, which, however, communicate here in particular via the interior of at least one container to be expanded. In this situation, for example, a gas which is used to cool a container to be expanded or an already expanded container can in turn be made available to a further forming station. In other words, the air flowing through the stretching rod is used for cooling in at least one period of time and at the same time is made available at least indirectly to another blowing station or forming station. An existing flow connection between the gas supply devices is understood in particular to mean that valves in the area of the flow connection are at least partially open.

In an advantageous embodiment, a compressor device is provided which supplies at least one gas supply device with compressed air and which preferably also supplies the second gas supply device with compressed air at least temporarily. The second gas supply device can particularly preferably be fed by the compressor during the starting process of the blow molding machine.

In addition to the two gas supply devices mentioned above, further gas supply devices can also be provided to supply the forming stations. For example, a gas supply device can be provided in the form of a pre-blow channel and/or in the form of a ready-blow channel and/or in the form of a PI channel and/or in the form of an (air) supply channel.

The transport device is advantageously a rotatable transport device and in particular a blowing wheel on which at least the two forming stations are arranged. A large number of forming stations are advantageously arranged on the transport device, for example eight forming stations, twelve forming stations or the like.

Advantageously, the above-mentioned forming stations each have blow molds into which the plastic preforms can be introduced to expand them and from which the subsequently manufactured containers can be removed again. These blowing stations are advantageously hinged, in particular hinged, in order to then be able to introduce a plastic preform.

In a further advantageous embodiment, the blowing stations each have a blowing nozzle, which can be placed on a mouth of the containers to be expanded. As mentioned above, a Flow path of the expansion medium, in particular the blown air, at least in sections through the stretching rod. Another flow path advantageously runs between the stretching rod and a wall of the plastic container, in particular between an outer circumference of the stretching rod and a mouth of the container to be expanded.

A control is advantageously provided which enables the blown air to be guided in both directions, i.e. into the container and out of the container, for at least one of these two flow paths, advantageously for both flow paths.

In a further advantageous embodiment, the pressure ratios of the first gas supply device and the second gas supply device are at least temporarily selected such that the pressures made available by these gas supply devices at least temporarily change by less than 30%, preferably by less than 20% and particularly preferably by less than 10% different from each other. In this way, it is possible for an area of the container, in particular the base, to be cooled at the same time during a phase of the expansion process, in particular during a stabilization phase. Advantageously, at least during this phase, a pressure provided by the first gas supply device at a specific forming station is temporarily slightly higher than the pressure provided by the second gas supply device. It would be possible for at least one gas supply device and preferably both gas supply devices to be designed as pressure channels which supply a number of forming stations and particularly preferably all forming stations of the device with compressed air.

In a further advantageous embodiment, the second forming station is arranged downstream of the first forming station in relation to the transport movement of the plastic preforms or plastic containers. This means that the container that is already cooled in the first forming station is already further advanced in the manufacturing process than the container arranged in the above-mentioned second forming station. This means that a blast air flow flows from the first preceding forming station to a second subsequent forming station. In other words, the flow that is used to expand and/or cool a first plastic container can preferably also be used to expand and/or stabilize a second plastic container.

Such a flow can be achieved by appropriately connecting valves.

In a further advantageous embodiment, the first gas supply device temporarily provides the pressurized gaseous medium (in particular the medium available to the second forming station) for the expansion and/or stabilization of a plastic container arranged in the second forming station. Both gas supply devices are advantageously in flow connection - preferably at different time intervals - with different forming stations or the plastic preforms located in these forming stations.

The first gas supply device can also make the gas available to the second forming station via the first forming station or via the container located in the first forming station (and/or directly).

In a further advantageous embodiment, the device has a control device which causes the period in which the first gas supply device makes the gaseous medium available to the first forming station and the period in which the first gas supply device makes the gaseous medium available to the second forming station are at least partially offset.

In a further advantageous embodiment, the device has a control device which causes the period in which the first gas supply device makes the gaseous medium available to the first forming station and the period in which the second gas supply device makes the gaseous medium available to the second forming station represents at least partially simultaneously and/or offset.

This means that the plastic containers are expanded at different times. The control device can be, for example, a valve control, which valves of the Bla process controls. Advantageously, at least one and preferably several valves are assigned to each individual forming station. The control device can control the blowing processes in the individual forming stations by appropriately controlling these valves. This control device is advantageously designed in such a way that air is also temporarily fed into the plastic containers via the individual stretching rods or rinsing rods.

In a further advantageous embodiment, the device has a plurality of forming stations, and all of the forming stations are at least temporarily in flow connection with the first gas supply device. Advantageously, all of the forming stations are also at least temporarily in flow connection with the second gas supply device. This flow connection can be established via the blowing nozzles, which are components of the individual forming stations.

In a further advantageous embodiment, as mentioned above, at least one gas supply device is a channel and preferably an annular channel.

In a further advantageous embodiment, at least one stretching rod has a gas outlet opening in an end section of the stretching rod. Cooling of the bottom of the containers can be achieved via this opening. The end section of the stretch rod is advantageously an end section which is brought to the bottom of the containers during the forming process. This end section advantageously serves to expand the container by stretching it along a longitudinal direction. This opening is preferably the only opening of the stretching rod, which can also be referred to as a rinsing rod. However, it would also be conceivable for several openings, for example oblique openings, to be arranged through which the gaseous medium can exit in a direction oblique to the longitudinal direction and in particular directed towards the bottom of the containers.

The present invention is further directed to a method for expanding plastic containers, wherein the plastic containers are expanded by means of a plurality of forming stations by applying a gaseous medium and the gaseous medium is provided by a first gas supply device and a plastic container located in a forming station is fed at least temporarily through a stretching rod.

According to the invention, at least temporarily during the supply of the gaseous medium to the plastic container located in the first forming station, this first forming station is in a flow connection with a second gas supply device and this second gas supply device is at least temporarily in flow connection with a second forming station. A flow connection between this second gas supply device and the first gas supply device runs at least in sections between a stretch rod and a mouth of the container.

It is therefore also proposed on the process side that the pressure of a gaseous medium, which is used for bottom cooling or area cooling of the containers, is also used for a further forming station for expanding the containers.

The containers are advantageously transported during their expansion. Particularly preferably, the second forming station is arranged along a transport path of the containers behind the first forming station.

In a further advantageous method, the supply of the gaseous medium is directed to this container section through the stretching rod in order to stabilize a container section. In particular, the container section is a bottom of the container.

Advantageously, at least at times, the first gas supply device has a pressure that is at most 30%, preferably at most 20% and preferably at most 10% higher than the second gas supply device.

In particular, due to these relatively small pressure differences, a targeted cooling of a container can be carried out with a pressure supply to another container, in particular at the same time.

The container is advantageously expanded by exposure to a gaseous medium before the gaseous medium is fed through the stretching rod. This means that the circuits described here, ie the use of pressure to cool the container, are only used specifically with or after the container has actually been formed.

Advantageously, the container is initially subjected to a pre-blow pressure, particularly preferably then with a finished blow pressure, which is used to shape the container and finally with a pressure which is intended to stabilize the shaped container.

In a further advantageous method, the container is relieved of pressure after its expansion and preferably a gas produced as part of this pressure relief is passed through the stretching rod at least temporarily. This means that this period of pressure relief can also be used to further cool the container or its base.

The expansion of the plastic container in the first forming station and the expansion of the plastic container in the second forming station advantageously take place at a time offset from one another.

In a further advantageous method, different pressure levels are also provided when producing the plastic containers.

In a further advantageous method, essentially (or almost) the same pressure level prevails at least temporarily and preferably constantly during a finished blowing of a container and/or during a rinsing of the container in the first gas supply device, in the container and in the second gas supply device.

This means that these pressure ratios or pressures increase during these mentioned phases of finish blowing and/or rinsing (preferably during both phases) by less than 30%, preferably by less than 20%, preferably by less than 10% and preferably by less differ from each other by more than 5%. This small pressure difference makes it possible to specifically maintain the internal pressure of the container and at the same time allow a small flow of media to cool the bottom area. It is possible for the pressure to drop gradually from the second gas supply device towards the first gas supply device (or, if desired, in the opposite direction).

• Darin zeigen:
  • 1 eine schematische Darstellung eines Umformungsvorgangs nach dem Stand der Technik;
  • 2 eine schematische Darstellung eines erfindungsgemäßen Umformungsvorgangs;
  • 3a, 3b eine Darstellung eines erfindungsgemäßen Blasformvorgangs in einem kontinuierlichen Betrieb;
  • 4a, 4b eine Darstellung eines Blasformvorgangs zu Beginn oder nach einer entstandenen Lücke;
  • 5a, 5b die Darstellung eines Blasformvorgangs am Ende eines Prozesses bzw. bei dem letzten Behältnis vor einer Lücke;
  • 6a, 6b einen kontinuierlichen Betrieb bei einer anderen Ausführungsform der Erfindung;
  • 7a, 7b einen Blasformvorgang zu Beginn oder nach einer Lücke für den in 6a, 6b beschriebenen Vorgang; und
  • 8a, 8b zwei Darstellungen für das letzte Behältnis in dem Blasformvorgang nach 6a, 6b.

Further advantages and embodiments result from the attached drawings:

• Show in it:
  • 1 a schematic representation of a forming process according to the prior art;
  • 2 a schematic representation of a forming process according to the invention;
  • 3a , 3b a representation of a blow molding process according to the invention in a continuous operation;
  • 4a , 4b a representation of a blow molding process at the beginning or after a gap has arisen;
  • 5a , 5b the representation of a blow molding process at the end of a process or at the last container before a gap;
  • 6a , 6b continuous operation in another embodiment of the invention;
  • 7a , 7b a blow molding process at the beginning or after a gap for the in 6a , 6b process described; and
  • 8a , 8b two illustrations for the last container in the blow molding process 6a , 6b .

1 shows a roughly schematic representation of a process flow according to the prior art. A blow molding machine with eight stations AH is shown here in rough schematic form. The letters indicate (as in 2 ) the following process states: A: Opened blow mold; B: Transferring a plastic preform into the blow mold; C: Formation of the container - in particular through pressurization; D: Container completed and maintained under pressure; E: Container completed and maintained under pressure; Q: Container completed and maintained under pressure; G: Relieve the pressure on the container, H: Handover of the manufactured container from the blow mold.

The reference numeral 120 roughly schematically identifies a reservoir or a supply unit for pre-blow air and ready-blow air. The individual forming stations are preferably constructed identically and preferably move counterclockwise.

2 illustrates an embodiment of the invention. Here again is a blow molding machine 1 with the ones already referred to 1 stations described. Here, reference number 4 denotes the first forming station and reference number 6 denotes a second forming station. All forming stations are arranged on a common carrier or a common transport device.

While the in 1 The illustration shown shows the well-known principle with pre- and final blowing as well as pressure and cooling phases with subsequent relief, the second illustration shows a blowing wheel 14 with eight stations in the blowing process. However, an additional supply channel 22, ie the first gas supply device 22, is provided here.

At the in 2 In the situation shown, the purging air is introduced into the container 10 through a stretching rod 12, more precisely via a bottom 12a of the stretching rod 12. In this phase, the bottom 10a of the container is actively cooled from the inside. The gas supply device 22 is fed here directly by a compressor (not shown). In the method now proposed, the container is produced as before by means of pre- and final blowing, but the blown air now does not come directly from a compressor, but is redirected. More precisely, the blown air is led from a compressor into the first gas supply device 22. From there, the blown air is passed via the flushing or stretching rod 12, which preferably only has an opening in the bottom area 12a, through the already fully formed containers in the printing and cooling phase to a finished blowing channel 24, ie to the second gas supply device 24 . The air is guided between an outer circumference 12b of the stretch rod 12 and an inner wall of the mouth 10b of the container 10.

With such a feed, this first supply device 22 feeds the three forming stations marked with the letters D, E and F via the container itself. The containers 10, on the other hand, are under the finished blowing pressure (starting from the second gas supply device 24), so the situation is essentially the same Pressure level in the first gas supply device 22, in the containers (during the pressure and cooling phase) and the finished blowing channel or the second gas supply device 24. In this case, there is a type of open system when air flows. On the other hand, only as much air can flow through the containers as is consumed to produce the containers via the second gas supply device 24, i.e. the finished blowing channel.

This process is shown by the solid arrows V1 to V5.

During the relief process, i.e. here in the forming station, which is marked with the letter G, air can initially flow out of the container again, for example via the stretching or rinsing rod 12, more precisely through the channel 14 located in the stretching rod, and thus are preferably recycled into the intermediate blowing channel. This flow is shown here by the arrows R1 to R3. In this way, a cooling effect can be generated again in the bottom area 10a of the container. The air emerging in this way is collected via a further gas supply device 26 (so-called air wizards) and can be further processed in a known manner. On the other hand, the air from the container can also be released into an outlet channel. This air can then be passed over the mouth of the container. The air then passes from the finished blowing channel into the second forming station 6 marked with the letter C and is also used in this area to form the container.

In order to generally ensure the highest possible efficiency of the blown air, it is possible to collect the respective relief air (forming station G) using air wizard systems or recycling systems. The air consumption is not increased as a result, but rather is used more effectively, since a passage is made through the already finished containers 10 in order to produce new containers. Furthermore, parallelization of the airways can be achieved since several flushing or stretching rods 12 can work at the same time. In this way, air consumption is not increased. The device according to the invention can thus generate bottom cooling of the plastic containers without additional air consumption.

Due to the ever higher station performance, the cooling time in the station during a blowing process automatically becomes shorter and shorter. The invention allows greater ground stability because the actual geometry of the ground shape is better preserved. The cooling effect is much more efficient due to the double effect, i.e. cooling from inside and outside (due to the flow of air through the horizontal bar in both directions) and therefore there is almost no deformation of the floor geometry.

There is also no need to wet the outer skin of the container with water, which is particularly advantageous for machines that are blocked or synchronized with one another. On the other hand, the container base 10a should also be cooled in front of a labeling machine (particularly in the case of so-called CSD containers), which has so far been done via post-cooling of the base with water. These water-soaked bottles are difficult to label.

Preferably the in 2 Stretching or rinsing rod shown is designed in several parts and preferably at least in two parts. It is possible for this stretching rod 12 to have a main segment, which can always have the same design. A corresponding molding segment or preform segment can be designed to be interchangeable using a suitable closure, for example a bayonet closure. This part of the flushing or stretching rod is the in 2 shown area, which also dips into the plastic preform.

In principle, it would also be possible to use one-piece flushing or stretching rods, which, however, would then usually have a standardized diameter (for example 14 mm). With these diameters, however, the stretching rod or rinsing rod cannot be immersed in all plastic preforms and therefore a divisible or composable rinsing rod is ideal here. This in 2 The preform segment of the stretching or rinsing rod shown can be provided with variable diameters, for example 8, 10, 12 and 14 mm. In this way, plastic preforms with different cross sections or diameters can also be manufactured.

The 3a and 3b show an illustration of a method according to the invention. The curve K refers to a pressure curve within the plastic preforms during a blow molding process. The blow molding process here has several phases or sections I to V. The reference numbers P1, P2, BK, Exh1 and Exh2 identify several valves, namely the valves for a pre-blow pressure (P1), for a ready-blow pressure (P2), ie the second gas supply device 24, the valve for the supply channel (BK) and two outlet valves Exh1 and Exh2. During the blowing process, the container is first pre-blown in stage I of the process. In this area the pressure increases to a level of approx. 3-7 bar. The containers are then completely molded in a relatively short section II, which corresponds to the procedure in 2 shown forming station 6, which is also provided with the symbol C. In a further, longer phase III, a certain pressure is maintained in the container in order to stabilize it. This corresponds to 2 the forming stations D, E and F. In addition to the valves or channels shown, another channel can also be provided which supplies a pressure cushion (preferably located in the forming stations) with compressed air. Such pressure pads are used to press the two blow molded parts together more strongly during the expansion process.

The container is then relieved of pressure (stage 4) and finally, in the last stage 5, any remaining air can be released via an outlet valve. The rectangles in the respective 3a , 4a , 5a , 6a , 7a and 8a illustrate the state in which the respective valves are opened. A difference to the prior art can be seen in particular in section 3, in which the container is supplied with compressed air both via the finished blowing channel (past the stretching rod) - ie via the second gas supply device - and via the first gas supply device 22 (through the stretching rod ), with an approximate equilibrium between the two feeds.

In general, in the context of this application, a gas supply device is understood to mean a device which can provide a gas, in particular air, in particular as a working gas. This gas supply device can preferably provide the gas at a pressure above atmospheric pressure. The gas supply devices described here are therefore also advantageously designed as gas reservoirs, which can store gas - in particular under the pressure mentioned above.

In the lower part of the picture a compressor 30 is shown schematically as well as various reservoirs or channels. In detail, reference number 32 denotes a pre-blowing channel, reference number 24 denotes a finished blowing channel or the second gas supply device, reference number 22 denotes the first gas supply channel and reference numbers 36 and 38 each indicate outlet channels. The compressor supplies the supply channel 22 with blown air.

Reference number 44 denotes a valve with which the supply of blown air to the first gas supply device can be controlled.

Thus refers 3a on continuous operation of the system. It can be seen that first the valve P1 for the pre-blow channel is opened and then at the beginning of section II the valve for the finished blow channel is also opened. As soon as a maximum pressure is reached, the valve BK for the supply channel is now also opened. These two valves are each kept open while the container is being stabilized and, as mentioned above, have similar pressures, although the pressure in the supply channel is preferably slightly higher, so that a flow towards the finished blowing channel or the second gas supply device 24 can take place .

After the end of section III, both the valve P2 and the valve BK are closed and, on the other hand, the valve P1 is opened again so that air can flow back into the pre-blowing channel 32. In this way, air pressure recycling can be achieved. From section V onwards, valve P1 is also closed and the two exhaust valves Exh1 and Exh2 are also opened. This residual air can be released from the system to the outside. The pressure in the pre-blow channel is lower than that in the first and second gas supply devices 22, 24.

The 4a , 4b show the special case in which work is just starting or a first container is being formed. In this situation, all channels 32, 24 and 22 are supplied with compressed air by the compressor 30 in order to achieve a certain pressure level. The actual in 4a However, the work process presented corresponds to that also with reference to 3a described work process. Here, additional valves 44, 46, 48 can be attached between the compressor 30 and the first and/or second gas supply device 24, 22 and the pre-blow channel 32 in order to control the supply of compressed air to the channels.

In addition to the valve 44, the valves 46 and 48 are also shown here, which control the air supply to the second gas supply device 24 and the channel 32.

The 5a and 5b show the special case of the expansion of the last container. In this situation, the compressor 30 only supplies the first gas supply device 22 with compressed air, ie the supply channel. In this situation, however, the wiring of the valves P1, P2, BK, Exh1 and Exh2 is modified. While only the valve P1 is opened here at the beginning of the blowing process, in the last container the valve P2 is only opened during section II and then closed again and the valve for the first gas supply device 22 is opened during section III. In order to achieve a certain flow through the container here, the first outlet valve Exh1 is also opened in section III. After the container has been formed, the outlet valve Exh2 is also opened.

The 6a and 6b show another modified process sequence. Specifically, section II is divided into two subsections IIa and Ilb and section IV is also divided into sections IVa and IVb. In section IVa, the blown air is preferably moved backwards through the rinsing or stretching rod. On the device side, the device here also has an additional channel 40 in addition to the channels already mentioned. This channel is referred to below as the PI channel. This channel is also assigned its own valve PI. In addition, an additional valve 42 is also provided here. This valve can be equipped as a check valve in the direction of the first gas supply device. Furthermore, it is also possible for this valve 42 to have two different switching positions gen allowed, whereby in the switching position 1 flow from the container into the second gas supply device 24 is possible and in the switching position 2 a flow from the container into the pl channel 40 is possible. The residual pressure remaining in the container can be processed in a known manner. In particular, this residual pressure can be directed or recycled into the pre-blow channel 32. The residual pressure subsequently present in the container can then be directed via the outlet channels 36, 38, with simultaneous opening of both outlet channels 36, 38 being preferred.

Also in the in 6a This becomes clear in the diagram shown, where in section IIa only the valve PI is opened and in section III the valve 42 is switched in such a way that air can get from the container on the one hand into the second gas supply device 24 and on the other hand into the PI channel . In the area IVa, the valve 42 is switched and air can now enter the PI channel 40. In this phase, a backward movement can be carried out by the stretching rod 12 and in this way further cooling of the floor can be carried out.

The 7a and 7b again show a representation similar to that in the 4a situation shown, ie the machine is just starting to operate, although the additional PI channel 40 is also provided here. We therefore turn to the description for a procedure 4a referred. First, the pre-blow channel 32 is fed directly by the compressor 30, so the container is pre-blown first. The compressor 30 then feeds the PL channel 40, which further expands the container. In order to fully expand the container, the compressor 30 feeds the second gas supply device 24. The compressor 30 then feeds the first gas supply device 22, from which the air in the first switching position of the valve Vneu is passed through the container into the second gas supply device 24 becomes. This creates a continuous and calm cooling effect at the bottom of the container. In the subsequent second switching position of the valve Vneu, a further part of the residual pressure remaining in the container is preferably recycled into the PI channel 40. The flow of air runs from the container through the flushing rod into the PI channel 40. The residual pressure still present in the container is then further processed in a known manner, for example by recycling the air into the pre-blow channel 32. The residual pressure that was last present in the container can now be directed via the container mouth to the outlet channels 36, 38.

The 8a and 8b again show a situation similar to that in 5a and 5b situation shown, i.e. the last container to be expanded in the production run, but here again for a device with the additional PI channel. We therefore also refer to the above description of the figures ( 5a , 5b) referred. The container will be as in 5a and 5b first expanded through the pre-blowing channel 32, the PI channel 40 and the second gas supply device 24. The valve Vneu then switches to the first switching position, so that the air from the first gas supply device 22, which is fed directly from the compressor 30, is directed through the container into the already open outlet channel 36. As a result, on the one hand, the required cooling effect of the floor is achieved, and on the other hand, a diversion into the outlet channel 36 is achieved. The outlet channel 36 is preferably designed in such a way that a continuous and calm air flow and thus container cooling is achieved. In the second switching position of the valve Vneu, the air in the container is first recycled into the PI channel 40. This flow preferably takes place backwards over the flushing rod. It can then be recycled in a known manner, in particular in the pre-blow channel 32. Following this, both outlet channels 36, 38 are preferably opened simultaneously in order to completely relieve the container. The two outlet channels are therefore preferably designed in such a way that they allow a different flow quantity and/or flow speed for the emerging gas. The outlet channel 38 advantageously allows a faster outlet of the emerging gaseous medium (or has a larger flow cross section) than the outlet channel 36.

The applicant reserves the right to claim the features disclosed in the application documents as essential to the invention if, individually or in combination, they are new compared to the prior art.

Reference symbol list

1

blow molding machine

4

first forming station

6

second forming station

10

container

10a

container bottom

12

Stretching/rinsing rod

12a

Bottom of the horizontal bar/washing rod

12b

Outer circumference of the horizontal bar/washing rod

14

blow wheel

22

first gas supply facility

24

second gas delivery device

26

third gas supply facility

30

compressor

32

Pre-blow channel

36, 38

Exhaust channels

40

PI channel

42

Valve

44, 46, 48

Valve

120

reservoir

UH

Stations of a process sequence

V1-V6

Air flow during injection

R1-R4

Air flow during the unloading process

K

Curve

P1

Valve for pre-blow pressure

P2

Valve for ready blowing pressure

BK

Valve for first provision device

Exh1, Exh2

Exhaust valves

I-V

Procedural stages, sections

IIa, IIb

Division of Section II

IVa, IVb

Division of Section IV

Claims (20)

Device (1) for expanding plastic containers (10) with a transport device (14), which transports the plastic containers (10) along a predetermined transport path, with at least a first forming station arranged on the transport device (14) and transported by the transport device (14). (4), which expands the plastic containers (10) by applying a gaseous medium, with at least a second forming station (6) arranged on the transport device (14) and transported by the transport device (14), which expands the plastic containers by applying a gaseous medium expands, wherein the first forming station (4) and the second forming station (6) each have stretching rods (12) for stretching the plastic containers (10) to be expanded in their longitudinal directions and these stretching rods each have a channel through which the plastic containers (10) to be expanded are passed ) a gaseous medium can be supplied through the stretch rod (12) and with at least one first gas supply device (22), which at least temporarily provides the first forming station (4) with a pressurized gaseous medium, this gaseous medium being in the first Forming station (4) to expand plastic containers (10) can be fed at least temporarily through the stretching rod (12), characterized in that the device (1) has a second gas supply device (24), which has an interior of the in the first forming station (4 ) to be expanded plastic container (10) is in flow connection in such a way that between the second gas supply device (24) and the interior Gas flowing in the space of the plastic containers (10) flows between the stretch rod (12) and a wall of the plastic containers (10), the first gas supply device (22) and the second gas supply device (24) being arranged over the interior of the gas in the first forming station (4). Plastic container (10) is at least temporarily in flow connection and this second gas supply device (24) is also in flow connection with a plastic container (10) located in the second forming station (6), and the pressure conditions of the first gas supply device (22) and the second gas supply device ( 24) are selected such that a gas flow from the second gas supply device (24) to the first gas supply device (22) takes place at least temporarily, with a valve (P2) for the second gas supply device (24) and a valve (BK) for the first gas supply device (22) are kept open during the stabilization of the container (10), the air flowing through the stretch rod (12) being used for cooling in at least one period of time and at the same time being made available at least indirectly to a further forming station (4), and the blown air is led from a compressor into the first gas supply device (22) and from there is passed via the rinsing or stretching rod (12) through the already formed containers in the printing and cooling phase to the second gas supply device (24), so that the blown air for pre- and final blowing does not come directly from a compressor, but is redirected. Device (1) for expanding plastic containers (10) with a transport device (14), which transports the plastic containers (10) along a predetermined transport path, with at least a first forming station arranged on the transport device (14) and transported by the transport device (14). (4), which expands the plastic containers (10) by applying a gaseous medium, with at least a second forming station (6) arranged on the transport device (14) and transported by the transport device (14), which expands the plastic containers by applying a gaseous medium expands, wherein the first forming station (4) and the second forming station (6) each have stretching rods (12) for stretching the plastic containers (10) to be expanded in their longitudinal directions and these stretching rods each have a channel through which the plastic containers (10) to be expanded are passed ) a gaseous medium can be supplied through the stretch rod (12) and with at least one first gas supply device (22), which at least temporarily provides the first forming station (4) with a pressurized gaseous medium, this gaseous medium being in the first Forming station (4) to expand plastic containers (10) can be fed at least temporarily through the stretching rod (12), characterized in that the device (1) has a second gas supply device (24), which has an interior of the in the first forming station (4 ) to be expanded plastic container (10) is in flow connection in such a way that a gas flowing between the second gas supply device (24) and the interior of the plastic container (10) flows between the stretching rod (12) and a wall of the plastic container (10), the first Gas supply device (22) and the second gas supply device (24) are at least temporarily in flow connection via the interior of the plastic container (10) arranged in the first forming station (4), and this second gas supply device (24) is also in flow connection with one in the second forming station (6 ) located plastic container (10), and wherein the pressure conditions of the first gas supply device (22) and the second gas supply device (24) are selected such that at least temporarily there is a gas flow from the first gas supply device (22) to the second gas supply device (24), wherein in at least one period of time the air flowing through the stretch rod (12) is used for cooling and at the same time is made available at least indirectly to a further forming station (4), and the blown air is guided by a compressor into the first gas supply device (22) and from There it is passed via the rinsing or stretching rod (12) through the already fully formed containers in the printing and cooling phase to the second gas supply device (24), so that the blown air for pre- and final blowing does not come directly from a compressor, but rather is redirected. Device (1) according to Claim 1 or 2 characterized by a compressor device which supplies at least one gas supply device with compressed air. Device (1) according to the preceding claim, characterized in that the compressor device also supplies the second gas supply device (24) with compressed air at least temporarily, the second gas supply device (24) being able to be fed by the compressor when the blow molding machine is started. Device (1) according to Claim 2 or 3 , characterized in that the first gas supply device (22) is fed directly by the compressor in such a way that the gaseous medium is led from the compressor into the first gas supply device (22), and the gaseous medium from there via the stretch rod (12) through the plastic containers (10), in particular during a pressure and cooling phase, is directed to the second gas supply device (24). Device (1) according to at least one of the preceding claims, characterized in that the stretching rod (12) only has an opening in a bottom region (12a). Device (1) according to at least one of the preceding claims, characterized in that the gaseous medium is guided between an outer circumference (12b) of the stretching rod (12) and an inner wall of the mouth (10b) of the container (10). Device (1) according to at least one of the preceding claims, characterized in that the pressure ratios of the first gas supply device (22) and the second gas supply device (24) are selected such that the pressures provided by these gas supply devices differ by less than 30%, preferably differ from each other by less than 20% and preferably by less than 10%. Device (1) according to at least one of the preceding claims, characterized in that the second forming station (6) is arranged downstream of the first forming station (4) in relation to the transport movement of the plastic containers (10). Device (1) according to at least one of the preceding claims, characterized in that the first gas supply device (22) temporarily makes the pressurized gaseous medium available for expansion and/or stabilization of a plastic container (10) to be expanded in the second forming station (6). provides. Device (1) according to Claim 10 , characterized in that the device (1) has a control device which causes the period in which the first gas supply device (22) makes the gaseous medium available to the first forming station (4) and the period in which the first gas supply device (22) which provides the gaseous medium to the second forming station (6) are at least partially offset. Device (1) according to at least one of the preceding claims, characterized in that the device (1) has a plurality of forming stations, and all of the forming stations are at least temporarily in flow connection with the first gas supply device (22). Device (1) according to at least one of the preceding claims, characterized in that at least one gas supply device (22, 24) is an annular channel. Device (1) according to at least one of the preceding claims, characterized in that at least one stretching rod (12) has a gas outlet opening in an end section of the stretching rod (12). Method for expanding plastic containers, wherein the plastic containers are expanded by means of a plurality of forming stations (4, 6) by applying a gaseous medium and the gaseous medium is made available by a first gas supply device (22) and in a first forming station ( 4) located plastic container is at least temporarily fed through a stretch rod (12), characterized in that at least temporarily during the supply of the gaseous medium to the plastic container located in the first forming station (4), this first forming station (4) is in a flow connection with a second gas supply device (24) and this second gas supply device (24) is at least temporarily in flow connection with a second forming station (6), this flow connection extending in sections between the stretching rod (12) and a mouth of the container (10), in at least one Period of time the air flowing through the stretch rod (12) is used for cooling and at the same time is made available at least indirectly to a further forming station (4), and the blown air is led from a compressor into the first gas supply device (22) and from there is passed via the rinsing or stretching rod (12) through the already formed containers in the printing and cooling phase to the second gas supply device (24), so that the blown air for pre- and final blowing does not come directly from a compressor, but is redirected. Procedure according to Claim 15 , characterized in that the supply of the gaseous medium through the stretching rod (12) is directed to this container section in order to stabilize a container section. Procedure according to Claim 15 , characterized in that the container (10) is expanded by exposure to the gaseous medium before the gaseous medium is supplied through the stretching rod (12). Method according to at least one of the preceding claims, characterized in that the container (10) is relieved of pressure after its expansion, this pressure relief taking place at least temporarily through the stretching rod (12). Method according to at least one of the preceding claims, characterized in that the expansion of a plastic container (10) in the first forming station (4) and the expansion of a plastic container (10) in the second forming station (6) take place with a time delay. Method according to at least one of the preceding claims, characterized in that at least during a final blowing of a container (10) and/or during a rinsing of the container (10), essentially the same pressure level in the first gas supply device (22), in the container (10 ) and the second gas supply device (24).

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