Device and method for forming plastic preforms into plastic containers with an electrically or magnetically controlled blown air valve

Abstract

Device (1) for forming plastic preforms (10) into plastic containers (20), comprising at least one forming station (4) which has a blow molding device (12) in the interior of which the plastic preforms (10) can be expanded into the plastic containers (20) by being supplied with a flowable medium, which further comprises a rod-like body (8) which can be inserted into the plastic preforms (10) through the opening of the plastic preforms (10) in order to stretch them in a longitudinal direction (L), wherein the forming station (4) further comprises a supply unit (6) which supplies the plastic preforms (10) with the flowable medium for their expansion, wherein the supply unit (6) comprises at least one first valve device (60) which controls the supply of the flowable medium to the plastic preforms (10), wherein the valve device (60) comprises a valve body (62),which is movable in a predetermined direction of movement (B1) between at least two positions, and a drive device (64) for moving this valve body (62), wherein the direction of movement (B1) in which the valve body (62) is movable has a component in the longitudinal direction (L) of the plastic preforms (10), and the drive device (64) is an electrically and / or magnetically operated drive device (64), characterized in that the valve body (62) has a first closing element (72) which, in one position of the valve device (60), closes an opening (74) through which a fluid connection with an interior of the plastic preforms (10) is established, and which closing element (72) releases this opening (74) in a second position of the valve device (60), and wherein a compensating means (80) is provided.which at least partially compensates a force exerted by the flowable medium on the closing element (72), wherein the compensating means (80) can be acted upon by the flowable medium and a movement of the compensating means (80) is at least partially coupled to a movement of the closing element (72).

Description

[0001] The present invention relates to a device and a method for forming plastic preforms into plastic containers. Such devices and methods are known, inter alia, from DE 10 2012 010 985 A1. In these processes, heated plastic preforms are typically fed into a forming device and expanded there by applying compressed air to form plastic containers, such as plastic bottles. The supply of compressed air to the plastic preforms is usually controlled by compressed air valves, which allow the supply of compressed air at different pressure levels.

[0002] To supply this compressed air, each blow molding station in the forming machine typically has a valve unit that controls the supply and, usually, the return of blowing air to and from the plastic preforms via valves. These valves are relatively large due to the pressure requirements and necessitate a very compact design to handle the high blowing pressures. This results in a relatively large dead space up to the blowing nozzle, which can be attached to the plastic preforms. This size of dead space also leads to a relatively high air consumption. In the following, dead space is defined as the space, particularly filled with gas, that serves solely to conduct a medium, especially blowing air, and that terminates at a valve element such as a piston.The gas contained in the dead space cannot be fully used to expand the plastic preforms, so efforts are made to minimize the dead space as much as possible.

[0003] The present invention aims to reduce this dead space. It also seeks to create a way to reduce the forces acting on the valves, even despite the high existing blowing pressures. Furthermore, it aims to enable more precise and faster valve switching.

[0004] These tasks are achieved according to the invention by a device and a method according to the independent claims. Advantageous embodiments and further developments are the subject of the dependent claims.

[0005] An inventive device for forming plastic preforms into plastic containers comprises at least one forming station, which in turn includes a blow molding unit inside which the plastic preforms can be expanded into the plastic containers by being supplied with a flowable medium, and in particular with a gaseous medium. Furthermore, the forming station has a rod-like body that can be inserted through the opening of the plastic preforms to stretch them in a longitudinal direction.

[0006] Furthermore, the forming station includes a supply unit which supplies the plastic preforms with a flowable medium for their expansion, wherein the supply unit has at least one first valve assembly which controls the supply of the flowable medium to the plastic preforms. This valve assembly further includes a valve body which is movable in a predetermined direction of movement between at least two positions and a drive device for moving this valve body.

[0007] According to the invention, the direction of movement in which the valve body is movable has a component in the longitudinal direction of the plastic preforms, and the drive device is, in turn, an electrically and / or magnetically operated drive device. By moving the valve body in the aforementioned direction, a reduction in dead space can be achieved, since, as explained in more detail below, the valve body can be brought very close to the actual blow nozzle or to the plastic preform to be expanded.

[0008] Advantageously, the device features a carrier with a multitude of the forming stations described above. This is, in particular, a rotatable carrier.

[0009] In a further advantageous embodiment, each of the forming stations has a blow nozzle which can be attached to an opening of the plastic preforms in order to supply them with the flowable medium, in particular a gaseous medium and especially with blowing air.

[0010] In a further advantageous embodiment, the direction of movement (of the valve body) forms an angle with the longitudinal direction of the plastic preforms that is less than 60°, preferably less than 50°, more preferably less than 40°, particularly preferably less than 30°, more preferably less than 20°, and most preferably less than 10°. In a further advantageous embodiment, the direction of movement is essentially parallel to a longitudinal direction of the plastic preforms to be expanded or also parallel to a direction of movement of the stretching rod that is inserted into the plastic preforms. This design allows for a very favorable reduction in the dead space volume.

[0011] In a further advantageous embodiment, the valve body extends at least partially through a valve chamber that can be supplied with the flowable medium, which preferably serves to expand the plastic preforms. In particular, this valve chamber can be supplied with a pressurized gaseous medium.

[0012] Particularly preferably, the valve body has a first closing element which, in one position of the valve device, closes an opening through which a fluid connection with an interior of the plastic preforms is established, and which, in a second position of the valve device, releases this opening, wherein a compensation means is further provided which at least partially compensates a force exerted on the closing element by the flowable medium.

[0013] The first sealing element could be a valve piston or a valve tappet that closes the opening or opens it to allow the gaseous medium to enter the plastic preforms. Advantageously, the compensating agent is also exposed to the gaseous medium, or this is achieved by the gas pressure acting on the valve also acting on the compensating agent, thus exerting a force upon it.

[0014] Preferably, the compensating means is subject to the flowable medium, and a movement of the compensating means is preferably partially, and particularly preferably permanently, coupled to a movement of the closing element. As will be explained in more detail below, the compensating means could also be a piston that is also subject to the blowing air, but in a direction opposite to that in which the closing element can be moved to open the valve.

[0015] Advantageously, the valve chamber is arranged between the closing element and the compensating means. Preferably, the closing element is pressurized with compressed air at least temporarily, simultaneously with the compensating means.

[0016] As mentioned in more detail above, the aim is to reduce dead space by positioning a valve or valve body close to a blow nozzle or the plastic preform to be expanded. To achieve this, the valve body or sealing element preferably acts from above or from a direction further away from the plastic preform than the valve body or sealing element. Preferably, as mentioned above, a valve train is used to actuate the valve body. This drive unit, already mentioned above, can be, for example, an electric motor, such as a two-, four-, six-, or eight-pole DC motor that operates between at least two operating points. In particular, the drive unit is a four-pole DC motor.

[0017] Furthermore, to avoid having to work against the full pressure situation in the pressure chamber or valve chamber, the valve assembly preferably also includes a counter-piston that provides pressure compensation. This makes it possible to switch high pressures very quickly and very precisely with minimal air loss. The concentric design of the valve assembly is advantageous, with the aforementioned pull rod guided in a central area of ​​this valve chamber. The valve assemblies are preferably arranged circularly around this area in which the pull rod is guided. This ensures a sufficiently high volume flow rate.

[0018] The reduction of dead space described here enables very fast switching times and very precise switching points to be achieved cost-effectively, while also ensuring a long service life.

[0019] In a further advantageous embodiment, the compensating means and the closing element are arranged such that a force exerted on the compensating means by the flowable medium counteracts a force exerted on the closing element by the flowable medium. As mentioned above, a valve chamber can, for example, be arranged between the compensating means and the closing element. The resulting pressure thus acts in both directions of movement of the valve body, so that a net force can be generated. However, other compensating means would also be conceivable, such as spring devices that preload the valve body.

[0020] In a further advantageous embodiment, the compensating means and the closing element are arranged on a common support. Advantageously, this support projects through the valve chamber.

[0021] Advantageously, both the closing element and the compensating element substantially close the aforementioned valve chamber. "Substantially closed" means that at least complete closure is intended, although (minor) media flows may still occur. Advantageously, however, the compensating element closes the valve chamber regardless of its position or the position of the closing element. This means that, for example, whether the closing element closes its associated opening or not, the compensating element always seals the valve chamber. It would also be possible for the closing element and the compensating element to be designed such that, when acted upon by the gaseous medium, a resulting force is generated that forces the valve into a closed position.

[0022] In a further advantageous embodiment, the device has a second valve assembly that controls the supply of the flowable medium to the plastic preforms. This second valve assembly also has a valve body that is movable in a predetermined direction of movement between at least two positions, and a drive mechanism for moving this second valve body. Advantageously, the direction of movement in which the valve body is movable again has a component in the longitudinal direction of the plastic preforms. Here, too, an angle between this direction of movement and a longitudinal direction of the plastic preform is advantageously less than 60°, preferably less than 30°, and particularly preferably less than 15°.

[0023] Furthermore, a third valve could also be provided, which also serves to supply a flowable medium to the plastic preform. Even with just two valves, it is possible to apply different pressure levels to the plastic preform. It is advantageous to supply the plastic preform with different pressure levels of the gaseous medium. For example, a first valve assembly can control the supply of a pre-blow pressure to the plastic preform (e.g., with pressures in the range between 1 bar and 12 bar), the second valve assembly the supply of an intermediate blow pressure (e.g., with pressures in the range between 8 bar and 20 bar), and the third valve assembly the supply of a final blow pressure (e.g., with pressures in the range between 20 bar and 50 bar).Preferably, the directions of movement of the valve bodies of at least two valves that control the supply of blowing air to the plastic preforms are parallel to each other. Preferably, the directions of movement of the valve bodies of all valves that control the supply of blowing air to the plastic preforms are parallel to each other. Preferably, at least the valve assembly that serves to control the highest pressure level—in particular as a valve plunger or with a plunger—is arranged directly and / or as close as possible to the blow mold, since this allows for the greatest pressure savings, or the most efficient savings can be achieved by reducing the dead space that occurs in this process.

[0024] In a further advantageous embodiment, the device comprises at least one magnetic element whose movement is coupled to a movement of the valve body. For example, at least one magnetic element, such as a permanent magnet, could be arranged on the valve body or on a support that also carries the valve body. Alternatively, several such permanent magnets could be arranged one behind the other, particularly in the longitudinal direction of the valve body. These magnetic elements can interact with other magnetic elements, such as coils or electromagnets. Therefore, the device preferably also comprises stationary magnetic elements, such as, but not exclusively, electromagnets.By appropriately wiring the electromagnets, the position of the valve body can be changed, and thus, for example, the valve can be switched from a closed position to an open position.

[0025] Preferably, the device also has several such electromagnets, which are particularly preferably arranged one behind the other in the aforementioned longitudinal direction of the valve body.

[0026] In a further advantageous embodiment, the device has a circumferential sealing element that can be applied to an opening section of the plastic preforms, and at least one valve body is arranged within a cross-section formed by this sealing element. This valve body may be offset vertically from said cross-section, but it is located within a volume formed by this cross-section, in particular a cylindrical volume. In other words, a projection of the valve body in the aforementioned longitudinal direction would intersect the cross-sectional area.

[0027] Preferably, several valve bodies are arranged such that their projections would coincide with the aforementioned cross-sectional area. In a preferred embodiment, it is possible that the valve bodies, in an operating state, project into an opening area of ​​the plastic preforms.

[0028] However, it is also possible that the valve bodies are arranged above the sealing agent, or, with respect to the longitudinal direction of the plastic preform, are arranged further away from the plastic preform than the sealing agent itself. Preferably, the sealing agent can be an O-ring-like body.

[0029] In a further advantageous embodiment, the aforementioned pull-up bar is arranged between the valve bodies. In other words, the valve bodies can be arranged circumferentially around the pull-up bar.

[0030] In a further advantageous embodiment, the directions of movement of all valve bodies are parallel to a direction of movement in which the pull-up bar also moves. Advantageously, corresponding axes of movement of the valve bodies are thus parallel to an axis of movement of the pull-up bar, and particularly preferably, the axes of movement of the valve bodies are arranged around an axis of movement of the pull-up bar.

[0031] Generally, compressed air can be supplied via a delivery device such as a compressor or a building's mains supply. This compressed air can be fed via a rotary distributor to a rotating part of the machine, such as a blow wheel. At least one pressure modification device can be arranged on this blow wheel or the movable support. Preferably, several pressure modification devices are arranged, such as pressure reducers, which reduce the pressure supplied by the delivery device, particularly to predetermined levels. From these pressure reducers, the compressed air can be fed to several compressed air reservoirs. These compressed air reservoirs can, for example, be annular channels, which preferably move with the movable support on which the individual forming stations are arranged or are fixed to it.

[0032] Starting from these ring lines or reservoirs, the compressed air is divided among the individual conversion stations and enters a valve block or valve chamber in each case.

[0033] The present invention further relates to a method for forming plastic preforms into plastic containers. In this process, the plastic preforms are transported along a predetermined transport path and, during this transport, are supplied with a flowable medium in order to expand them. Furthermore, the supply of the flowable medium to the plastic preforms is controlled by means of at least one first valve assembly, wherein this first valve assembly comprises a valve body that is moved in a predetermined direction of movement between at least two positions by a drive unit.

[0034] According to the invention, at least one electrical and / or at least one magnetic element is used to move this valve body.

[0035] It is therefore proposed, from a procedural standpoint, that the valve bodies be driven electrically or magnetically. It is noted that the magnetic drive is preferably also an electric (or electromagnetic) drive, particularly if this magnetic drive includes electromagnets that are thus also supplied with electrical energy.

[0036] In another preferred method, a compensating agent is used to at least partially compensate for a force exerted on the valve body by the flowable medium. Advantageously, as explained above, this compensating agent is also subjected to the flowable medium. Advantageously, a flowable medium supplied to a valve chamber acts both on a valve body or a closing element of the valve body and on at least one component of the compensating agent.

[0037] Further advantages and embodiments are shown in the accompanying drawings. These show: Fig. 1 A schematic representation of a device according to the invention for forming plastic preforms into plastic containers; Fig. 2 a representation of a conversion station; and Fig. 3. A diagram illustrating the arrangement of a valve; and Fig. 4 a top view of the in Fig. 3 arrangements shown.

[0038] Fig. Figure 1 shows a representation of a device according to the invention for forming plastic preforms 10 into plastic containers 20. Plastic preforms 10 are fed to the actual forming device 1 via a feeding device 42, which may, for example, be a transfer star. This forming device 1 has a carrier 2 rotatable about an axis of rotation, on which the individual forming stations 4 are arranged, in particular, at equidistant intervals. During transport on the forming station 4, the plastic preforms are subjected to compressed air such that they are formed into plastic containers 20. The expanded or manufactured plastic containers 20 are then removed via a discharge device 44, which may also be a transfer star.

[0039] Fig. Figure 2 shows a schematic representation of a single forming station 4 or a part thereof. This station has a supply unit 6, which serves to supply the plastic preforms with a gaseous medium, and in particular with blowing air. Reference numeral 12 roughly schematically denotes a blow mold within which the plastic preforms are expanded to form the plastic containers. This blow molding device 12 can have two side parts which can be pivoted relative to each other in order to receive the plastic preforms into a cavity formed therein and expand them. Reference numeral 14 denotes a blow nozzle device, which can be attached, for example, to an opening or a support ring of the plastic preform in order to supply it with blowing air. Reference numeral 16 denotes a valve block in which several valves are located for controlling the blowing air or...whose feed to the plastic preforms is arranged.

[0040] Reference numeral 8 denotes a pulley bar that is inserted into the interior of the plastic preform to stretch it longitudinally, particularly during the application of compressed air. Reference numeral 18 denotes a drive device for powering this pulley bar. This drive device 18 could, for example, be an electric motor. Alternatively, the pulley bar could have a pneumatic and / or cam-driven drive. Reference numeral L denotes a direction of movement of the pulley bar 8 and also a longitudinal direction of the plastic preform to be expanded.

[0041] Fig. Figure 3 shows a schematic representation of a device according to the invention. Here again, the pull-up bar 8 is shown, which is movable in the longitudinal direction L. This pull-up bar 8 is guided in a guide device 9, which also includes sealing devices 11 that seal the movement of the pull-up bar 8.

[0042] In contrast to the prior art, the valve assemblies 60 and 90 are arranged here such that their valve bodies 62, 92 also move in the longitudinal direction L, i.e., parallel to the direction of movement B1, to open and close the valves. Reference numerals 72 and 102 respectively designate closing elements that serve to close and open the openings 74 and 94, respectively, and thus to release the compressed air supply to the plastic preform (not shown).

[0043] Reference numeral 22 designates a valve chamber that can be pressurized with compressed air. This compressed air can originate from a reservoir, such as an annular channel. The valve bodies 62, 92 each have supports 63, 93, and magnetic elements 65, 95 are arranged on these supports. In addition to the valve bodies 62, 92 shown here, further valve bodies may be provided, which are located, for example, in front of and behind the plane of the figure.

[0044] These magnetic elements 65 and 95 are preferably permanent magnets. Reference numerals 64 and 104 denote drive devices intended for driving the valve body. A plurality of coils can be provided which, with appropriate wiring, attract the permanent magnets 65 and 95 respectively, such that the valve body 62, 92 is moved between two predetermined positions, for example, between two end positions, upwards and downwards. To define or fix these end positions, stop devices can be provided, for example. A stop can be arranged on the compensating element, for instance, to define the end position.

[0045] Reference numeral 80 designates a compensation device that counteracts the forces caused by the blown air or the air pressure itself. It is important to note that this air pressure would otherwise force the valve body 62, 92 or the closing elements 72, 102 downwards, or into an open position of the valve. Therefore, the actuators 64, 104 would generally have to exert high forces to counteract this pressure. For this reason, an additional piston element 80 is provided, which is arranged at the opposite end of the valve chamber 22. The air pressure acts on this compensation device 80, so that the resulting force acting on the valve body 62, 92 is kept relatively low. In this case, the actuator 64 or 104 only needs to exert relatively small forces to open or close the valve.

[0046] In particular, the surfaces of the closing unit and the compensation device 80 located within the valve chamber 22 are essentially the same size. This allows a "floating" state of the valve body 62, 92 to be achieved when the pressure increases within the valve chamber 22. The actuator 64, 104 therefore no longer has to work against the applied pressure and thus requires less force. This also leads to faster and more precise switching times of the valves. The reference numeral 30 refers to a sealing device, which is arranged circumferentially here and which can, for example, be applied to an opening edge of the plastic preform. The individual valve bodies 62, 92 or closing elements 72, 102 are arranged completely within the cross-section formed by this sealing device 30 (which is perpendicular to the plane of the figure). In this way, a very compact design can be achieved.The valve bodies 62 and 92 can also be brought very close to the plastic preform or the interior of the plastic preform to be expanded.

[0047] Fig. 4 shows a top view of the Fig. The arrangement shown in Figure 3 is as follows. In the center, the pull rod 8 is guided by the guide device 9. The actuators are not shown here. Also shown are two valve tappets or carriers 63 and 93. It is conceivable, for example, that only the final blowing is carried out via valve tappet or carrier 63 or 93, while pre-blowing and intermediate blowing are carried out, for example, via standard valves. However, it would also be conceivable that pre-blowing and final blowing are carried out via two of these valve tappets 63 and 93. Reference numerals 72 and 102 again refer to the closing elements.

[0048] In particular, the device or valve shown can also be used in a filling device, where the filling valve can regulate the feed of the product to be filled. It would also be possible to use multiple valves to allow the feeding of different components of a beverage into a container.

[0049] Preferably, the filling valve includes a sensor, in particular a sensor arranged on the valve stem, which makes it possible to move not only to two end positions (open-closed) but also to any position in between. This also makes it possible to dispense the product to be filled. A swirl element can preferably be mounted below the filling valve to ensure that the product to be filled flows regularly into the container. The applicant therefore reserves the right to also claim the design of the present valve device in connection with filling devices.

[0050] The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they are novel individually or in combination compared to the prior art. Reference symbol list 1. Conversion unit 4 conversion stations 6 operating units 8 horizontal bar 9. Guide system 10 plastic preforms 11 sealing devices 12 blow molds 14 blow nozzle assembly 16 Valve block 18 Drive unit 20 plastic containers 22 Valve chamber 30 Sealing device 42 Feeding device 44 Discharge device 60, 90 valve devices 62, 92 Valve body 63, 93 carriers 64, 104 Drive units 65, 95 magnetic elements / permanent magnets 72, 102 locking elements 74, 94 openings 80 Compensation device / piston element L Direction of movement of the horizontal bar / longitudinal direction B1 Direction of movement of the valve bodies

Claims

[1] Device (1) for forming plastic preforms (10) into plastic containers (20), comprising at least one forming station (4) which has a blow molding device (12) in the interior of which the plastic preforms (10) can be expanded into the plastic containers (20) by being supplied with a flowable medium, which further comprises a rod-like body (8) which can be inserted into the plastic preforms (10) through the opening of the plastic preforms (10) in order to stretch them in a longitudinal direction (L), wherein the forming station (4) further comprises a supply unit (6) which supplies the plastic preforms (10) with the flowable medium to expand them, wherein the supply unit (6) comprises at least one first valve device (60) which controls the supply of the flowable medium to the plastic preforms (10), wherein the valve device (60) comprises a valve body (62),which is movable in a predetermined direction of movement (B1) between at least two positions, and a drive device (64) for moving this valve body (62), wherein the direction of movement (B1) in which the valve body (62) is movable has a component in the longitudinal direction (L) of the plastic preforms (10), and the drive device (64) is an electrically and / or magnetically operated drive device (64). characterized by, that the valve body (62) has a first closing element (72) which, in one position of the valve assembly (60), closes an opening (74) through which a fluid connection with an interior of the plastic preforms (10) is established, and which closing element (72) releases this opening (74) in a second position of the valve assembly (60), and wherein a compensating means (80) is provided which at least partially compensates a force exerted by the flowable medium on the closing element (72), wherein the compensating means (80) is subject to the flowable medium, and a movement of the compensating means (80) is at least partially coupled to a movement of the closing element (72). [2] Device (1) according to claim 1, characterized by , that the direction of movement (B1) with the longitudinal direction (L) of the plastic preforms (10) forms an angle that is less than 30°. [3] Device (1) according to at least one of the preceding claims, characterized by , that the valve body (62) extends at least sectionally through a valve chamber (22) which can be acted upon by the flowable medium. [4] Device (1) according to claim 4, characterized by , that the compensating means (80) and the closing element (72) are arranged such that a force applied to the compensating means (80) by flowable medium counteracts a force applied to the closing element (72) by the flowable medium. [5] Device (1) according to at least one of the preceding claims, characterized by, that the device (1) has a second valve assembly (90) which controls the supply of the flowable medium to the plastic preforms (10), wherein the valve assembly (90) has a valve body (92) which is movable in a predetermined direction of movement (B1) between at least two positions and a drive assembly (94) for moving this valve body (92), wherein the direction of movement (B1) in which the valve body (92) is movable has a component in the longitudinal direction (L) of the plastic preforms (10). [6] Device (1) according to at least one of the preceding claims, characterized by , that the device (1) has at least one magnetic element (65, 95) whose movement is coupled to a movement of the valve body (62). [7] Device (1) according to at least one of the preceding claims, characterized by, that the device (1) has a circumferential sealing means (30) which can be applied to an opening section of the plastic preforms (10) and at least one valve body (62, 92) is arranged within a cross-section formed by this sealing means (30). [8] Method for forming plastic preforms (10) into plastic containers (20), wherein the plastic preforms (10) are transported along a predetermined transport path and are supplied with a flowable medium during this transport in order to be expanded, and wherein the supply of the flowable medium to the plastic preforms (10) is controlled by means of at least one first valve device (60), wherein this first valve device (60) has a valve body (62) which is moved in a predetermined direction of movement (B1) between at least two positions by a drive device (64), wherein at least one magnetic element is used to move this valve body (62). characterized by, that a force applied to the valve body (62) by the flowable medium is at least partially compensated by means of a compensating means (80), wherein the compensating means (80) can be acted upon by the flowable medium and a movement of the compensating means (80) is at least partially coupled to a movement of the closing element (72).

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