Device for generating process air and method for demolding molded parts of an injection molding

Abstract

The invention relates to an apparatus (100) for providing process air at at least two different pressure levels for an injection molding machine having an injection molding tool (10). The device (100) has two valves (Ia, IIa; ib, IIb), the first valve (Ia; ib) is connected, on the one hand, to a first pressure source (pI) at a first pressure level and, on the other hand, to an air duct (11a; 11b), which extends into the injection mould (10), and the second valve (IIa; iIb) is connected to a second pressure source (pII) at a second pressure level and to an exhaust line (12), wherein the first valve (Ia; ib) and a second valve (IIa; iIb) is designed and can be actuated in such a way that the air duct (11a; 11b) can withstand a first pressure or a second pressure. The invention further relates to an injection molding machine having such a device (100), to a method for demolding molded parts using such a device (100), and to the use of such a device (100).

Description

Field of the Invention

[0001] The present invention relates to a fluid technology device, which is applicable to injection molding machines that require process air and have high requirements for the repeatability of demolding. This is particularly applicable to the manufacture of sealed caps, but also relates to other applications. The present invention particularly relates to a device for generating or controlling process air, which can be used, for example, to manufacture open hollow bodies, such as rotating bodies or cup-shaped molded parts (injection molded parts, also referred to as molded parts), such as bottle caps. According to the present invention, process air is used at two different pressures. Thus, for example, first, for bending (i.e., shaping) the base of an open hollow molded part, pre-blowing at a first pressure is used, and for the subsequent ejection process of demolding by blowing the molded part out of the injection molding die, blowing at a second pressure having a value different from the first pressure is used. Background Art

[0002] In recent years, plastic caps have been widely used in the beverage industry. They are mainly produced on injection molding machines. During production on an injection molding machine, these caps are ejected from the injection molding die in a free-falling manner after reaching dimensional stability. Since the caps are mass-produced, not just one but multiple cavities are filled in each production cycle, and these cavities are arranged adjacent to and overlapping each other. Depending on the type of molded part or cap principle, the nature of the cavities and the type of ejection also vary. In the early stage of plastic cap production, the prior art was to unscrew the mold from the cap. Since this would take valuable production cycle time, nowadays, when the geometry permits, forced demolding of the cap is carried out. This means that they are pressed off the threads of the core, partly with mechanical support and partly with pneumatic support.

[0003] The ejection process and the dropping mode of the cap during ejection affect the process reliability and / or cycle time of the injection molding machine, where high process reliability and short cycle time can both improve the output and production volume of the injection process.

[0004] Compressed air is often used in the injection molding process of the lid. On the one hand, the so-called pre-blowing in the demolding stage is a technical process requirement to release the lid from the core by bulging the lid. For this purpose, when the mold is closed, compressed air is introduced between the lid and the core on the parting surface away from the thread between the end face of the core and the lid body. This can overcome the resulting vacuum, making it easier to separate the lid from the core. If the lid is separated from the core mechanically, in some cases, process air can be used via the same air connection by activating the compressed air in a short time near the ejection process to space the lid apart from the cavity. This helps ensure that the lid does not hit the mold components and thus safely leaves the injection molding die in a way that it falls freely towards the conveyor belt. However, the main ejection process is mechanical. The ejector moves forward at the same speed as the mold closing. Then, the moving side of the mold moves towards the rear end position as fast as possible. This forms a falling pattern similar to a waterfall. In existing injection molding machines, the pressure of the process air is usually always the same, i.e., the pre-blowing and the blowing have the same pressure.

[0005] The prior art ejects the produced lid during the opening movement of the injection molding die, thus saving valuable cycle time. The additional use of blowing helps to space the lid apart from the injection molding die, thereby increasing process reliability.

[0006] The ejection process is time-critical. The desired straight falling pattern is affected by various physical variables. Once the process settings are completed, the lid should always fall out of the injection molding die in the same falling pattern. If the process is disturbed or subject to fluctuations, the process reliability is affected. Such fluctuations in the pressure of the blowing may be caused by various actuators in the clamping unit, the ejector, or the blowing control system and may be physical or control-related characteristics. Fluctuations in the process air caused by changes in pressure and air flow time can cause the lid to no longer fall in the desired manner. The way the lid falls may be affected by the air pressure and the actuation time of the pneumatic valve. However, the blowing process is subject to few restrictions. If the lids fall into the air flow of the next lower cavity, they will rotate, swirl, or be blown too strongly in the direction of the nozzle side of the injection molding die half. This is why blowing is rarely used to blow off the lids. If the control of the blowing is too short, the lids will not be blown off. Changes in the air control and the associated unpredictable behavior increase the likelihood of process failures.

[0007] Since the currently used pneumatic valves traditionally have to manage two processes with only one pressure, on the one hand, pre-blowing to bend the base of the lid, and on the other hand, blowing to eject the lid and keep it spaced from the moving half of the injection molding die, the repeatability requirements for the pneumatic valves and all the axes involved are very high.

[0008] Therefore, in the field of injection molding machines, there is a need for (alternative) equipment and methods that achieve improved (e.g., more reliable) or simplified demolding of molded parts compared to currently known ways. Summary of the Invention

[0009] Accordingly, an object of the present invention is to provide a device for supplying process air to an injection molding machine, which can achieve improved demolding of molded parts. This object is achieved by the device according to claim 1. With the present invention, an injection molding machine can be equipped, which realizes the advantages of the present invention in production. Such an injection molding machine is according to claim 10. Furthermore, an object of the present invention is to provide an improved method for demolding molded parts, which is achieved by the method defined in claim 13. Finally, a use of the device according to the present invention is proposed. Such a use is disclosed in claim 17. Advantageous embodiments of the present invention are the subject matter of the dependent claims.

[0010] The device according to the present invention is for an injection molding machine having an injection molding die and is for supplying process air at a first pressure and at a second pressure different from (i.e., higher or lower than) the first pressure, and includes a series configuration of two valves, wherein the first valve is connected on the one hand to a first pressure source having the first pressure and on the other hand to an (air) duct that extends into the injection molding die, and the second valve is connected to a second pressure source having the second pressure and an exhaust line, and the first valve and the second valve are designed and controllable such that the (air) duct can be applied with the first pressure or the second pressure.

[0011] The concept of the present invention and the difference from known solutions is that, using the same pneumatic connection between the valve plate and the injection molding die, two different, (pre) - adjustable pressures (or pressure levels) are used. Although the injection molding die has only one effective duct for introducing process air (e.g., on the one hand for bending the molded part and using pre - blowing to break the negative pressure / vacuum between the surface of the molded part and the injection molding die, and on the other hand using blowing to blow away the molded part), which can of course occur multiple times, the present invention realizes a production process with two independent, (pre) - adjustable air supplies via one valve. The advantage thereof is an expanded adjustability, which increases the process window and reduces scatter, because fluctuations in the actuator or machine control have little relation to the droplet pattern, since the pressure for each process step (pre - blowing for tipping and blowing for ejection) can be set individually (in advance).

[0012] The device according to the present invention includes two independently switchable valves ( Figure 2The mutual or sequential connection (in series) of valve I and valve II) in [the device], where valve I is connected downstream of the other valve II in such a way that if valve II is actuated and in its basic position, it supplies the injection molding die with the pressure of valve II. This means that the injection molding die can be supplied with different pressures via the upstream and downstream valves, each valve being supplied with a different pressure. The two valves must never be actuated simultaneously, but this is absolutely impossible during the production process, and this can be ensured by appropriate control of the two valves, especially when the injection molding die is open, there should not be excessive pressure in the cavity.

[0013] In one embodiment of the device, the two valves are 3 / 2-way valves, which have three connections and two switching positions. The 3 / 2-way valves each have a first connection for connection to a supply line, a second connection for connection to a working line, and a third connection for connection to the exhaust port of the working line. In the first switching position, the first connection is closed, and the passage from the second connection to the third connection is open, and in the second switching position, the third connection is closed, and the passage from the first connection to the second connection is open. In this case, the first connection of the first valve is connected to a first pressure source, the second connection of the first valve is connected to an (air) duct, and the third connection of the first valve is connected to the second connection of the second valve. In addition, the first connection of the second valve is connected to a second pressure source, and the third connection of the second valve is connected to an exhaust duct for discharging (excess) process (waste) air.

[0014] In other embodiments of the device, two or more serially configured valves in a valve pair are connected in parallel. Each first valve in the valve pair is connected to a first pressure source, each second valve in the valve pair is connected to a second pressure source, especially to an exhaust duct, and each first valve in the valve pair is connected to the injection molding die, especially via an independent passage. Alternatively, each second valve in the valve pair can be connected to its respective exhaust duct.

[0015] With this parallel configuration of multiple pairs of valves, process air can enter the injection molding die via multiple air ducts, and then the process exhaust air can be discharged from the injection molding die in a large injection molding die when producing a large number of molded parts simultaneously.

[0016] In other embodiments of the device, additional valves (at least) are connected in series between the first valve and the second valve, wherein the additional valves are connected to an additional pressure source having a pressure different from that of the first and second valves (i.e., higher or lower or in between). Thus, the valves can take on more tasks. The first valve, the second valve, and the additional valves are designed and can be controlled such that the (air) duct can be pressurized with the first, second, or additional pressure. In particular, the additional valve can be a 3 / 2-way valve. The first connection of the additional valve is connected to the additional pressure source, the second connection of the additional valve is connected to the third connection of the first valve, and the third connection of the additional valve is connected to the second connection of the second valve.

[0017] By such an interconnection or succession / series connection (from valve pairs to "valve groups") of three or even more valves, process air at more pressure levels (3, 4, etc.) can be provided in order to be able to implement correspondingly more complex (demolding) processes.

[0018] In other embodiments of the device, the first pressure and / or the second pressure and / or any other pressure can be adjusted. In this way, the pressure / pressure level can be preset individually according to requirements, where they thus remain substantially constant during the operation of the injection molding machine. This means that the pressure / pressure level does not change during the process. Thus, process air can be introduced into the injection molding die at a selected pressure (from the preset pressures of various pressure sources) by correspondingly controlling the valves. Therefore, compared with a conventional system having only one pressure source and an adjustable pressure control valve, the switching between different pressures can be performed faster and more precisely.

[0019] In other embodiments of the device, the valves are electrically controllable, in particular solenoid valves.

[0020] In other embodiments, the device includes a control unit that is designed to activate (open or close) only one of the first and second valves and possibly additional valves in order to pressurize the passage with the first pressure or the second pressure or possibly an additional pressure.

[0021] This means that the valves can be precisely controlled in a desired manner using an electrical / electronic control unit. For example, complex processes (with multiple valves) can be flexibly programmed and monitored. This can in particular prevent unwanted situations, thereby increasing process reliability.

[0022] The present invention expands the possibility of influencing the process in additional aspects, for example, by connecting additional components, as described below.

[0023] In other embodiments, the device further includes a compressed air reservoir, which is connected to the first pressure source or the second pressure source and the first valve or the second valve, in particular to the first connection part of the first valve or the second valve.

[0024] The air blowing channel can be supported via the compressed air reservoir. This can reduce the sharp pressure drop when the valve is actuated (see Figure 2 Valve I), and stabilize the air flow by disconnecting the supply pipeline.

[0025] In other embodiments, the device further includes a check valve disposed in the exhaust pipeline, in particular further includes a muffler disposed in the exhaust pipeline, wherein the check valve is disposed between the second valve and the muffler, and in particular the pre-tightening force of the check valve is adjustable.

[0026] The exhaust port of the pneumatic circuit usually has a muffler. The check valve can be connected in the middle here. In this way, although the pre-blowing valve is turned off, the spring pressure corresponding to the check valve is still applied (see Figure 2 Valve II in, connection part 3). This can reduce the air consumption and prevent the air pipeline in the injection molding die from being completely emptied via the exhaust port. Therefore, the subsequent ejection process is more defined because less air is required for pressure accumulation.

[0027] As other aspects of the present invention, an injection molding machine having an injection molding die and the above device is proposed. The device is connected to the injection molding die via one or more (air) pipelines so as to be able to introduce process air under at least two different pressures into the injection molding die.

[0028] In one embodiment, the injection molding machine further includes one or more mechanical ejectors, for example in the form of a stripper ring, which are designed to separate the molded part from the surface of the injection molding die or the injection molding die and / or eject the molded part from the injection molding die to support the demolding process of the molded part.

[0029] In one embodiment, the injection molding machine is designed to produce open hollow bodies, such as rotating bodies or cup-shaped molded parts, in particular to produce a plurality of such molded parts simultaneously, wherein the injection molding die in particular has a plurality of cavities for forming the molded parts, and these cavities are arranged in columns adjacent to each other or in rows one above the other.

[0030] As a further aspect of the present invention, there is provided a method for demolding a molded part from an injection molding die in an injection molding machine as described above by means of the device as described above. The molded part is in particular an open hollow body, such as a rotating body or a cup-shaped molded part, for example a bottle cap. This method according to the invention comprises the following steps after the injection process, in particular during the cooling phase of the molded part in the injection molding die of the injection molding machine:

[0031] By opening the passage in the pre-blowing valve that connects the pre-blowing gas source to the pipeline, and by (previously) closing the passage in the blowing valve that connects the blowing pressure source to the pipeline, pre-blowing pressure is applied to the pipeline, in particular so as to introduce the pre-blowing gas into the injection molding die at the pre-blowing pressure, in particular so as to introduce it between each molded part and the core of the injection molding die when the injection molding die is closed, in particular so as to curl each molded part, in particular so as to break the vacuum between each molded part and the core, thereby separating the molded part from the injection molding die;

[0032] (Subsequently) By opening the passage in the blowing valve that connects the blowing pressure source to the pipeline, and by (previously) closing the passage in the pre-blowing valve that connects the pre-blowing pressure source to the pipeline, blowing pressure is applied to the pipeline, in particular so as to introduce the blowing gas into the injection molding die at the blowing pressure, in particular into the interior of an open hollow molded part, such as a rotating body or a cup-shaped molded part, so as to blow the molded part out of the injection molding die;

[0033] The injection molding die is exhausted by closing the passage in the blowing valve that connects the blowing pressure source to the pipeline, and by opening the respective passages in the pre-blowing valve and the blowing valve that connect the pipeline to the exhaust pipeline.

[0034] Here, the pre-blowing pressure can be one of the second pressure and the first pressure in the device, and conversely, the blowing pressure can be the other of the first pressure and the second pressure in the device. Accordingly, the pre-blowing gas source can be one of the second pressure source and the first pressure source in the device, and the blowing gas source can conversely be the other of the first pressure source and the second pressure source in the device. The pre-blowing valve can be one of the second valve and the first valve in the device, and conversely, the blowing valve can be the other of the first valve and the second valve in the device.

[0035] In one embodiment, the method comprises at least one of the following two additional steps:

[0036] Actuating a mechanical ejector to support the demolding process, in particular during or after applying the pre-blowing pressure to the pipeline, so as to separate the molded part from the injection molding die or the surface of the injection molding die;

[0037] Actuate a mechanical ejector to support the demolding process, especially before or during the application of blowing pressure to the pipe in order to eject the molded part from the injection molding die.

[0038] In other embodiments, the method has the following additional steps:

[0039] Support the blowing pressure via a compressed air reservoir to reduce the sharp pressure drop during the actuation of the blowing valve and stabilize the air flow by disconnecting the supplied blow pipe line (from the air source to the blowing valve).

[0040] In other embodiments, the method also has the following additional steps:

[0041] When the pre-blowing valve is closed, generate an (adjustable) spring pressure in the exhaust pipe line by means of a check valve to reduce the consumption of process air and prevent the complete evacuation of the pipe (leading to the injection molding die and especially in the injection molding die) via the exhaust pipe line.

[0042] It should be clearly noted that combinations of the above embodiments can constitute other embodiments of the present invention (provided that they are not mutually contradictory).

[0043] As other aspects of the present invention, there is proposed the use of the above device (for providing process air) for demolding a molded part from an injection molding die during manufacturing by means of an injection molding machine, the molded part being especially an open hollow body, such as a rotating body or a cup-shaped molded part, for example a bottle cap. Description of the Drawings

[0044] The following will further describe in detail non-limiting embodiments of the present invention with reference to the drawings. In the drawings:

[0045] Figure 1 is a schematic diagram (in the form of a pneumatic circuit or circuit diagram) of a prior art device for providing process air for demolding a molded part in an injection molding machine; and

[0046] Figure 2 is a schematic diagram (in the form of a pneumatic circuit or circuit diagram) of a device according to the present invention for providing process air for demolding a molded part in an injection molding machine (with multiple optional features).

[0047] In the figures, the same reference numerals represent the same elements. Detailed Description of the Embodiments

[0048] Figure 1A schematic diagram (in the form of a pneumatic circuit or pneumatic circuit diagram) of a known device for supplying process air for demolding molded parts in an injection molding machine is shown. Here, the process air is supplied from a single compressed air source p at a constant pressure. Based on this fixed output pressure of the compressed air source p, during the demolding process, the pressure of the process air is adjusted (e.g., reduced) according to the current requirements by means of a (proportional) pressure control valve 15, which is then fed into the injection molding die 10 via a single valve I and a (branch) pipeline 11 (via two process air inlets E1, E2). For this purpose, valve I is electrically actuated by a control unit, thereby opening a passage through valve I from port 1 to port 2 for the process air. During the demolding process, during the transition from pre-blowing for separating the molded part from the surface of the injection molding die 10 to blowing for ejecting the molded part from the injection molding die 10, for example, the pressure of the process air is reduced by means of pressure control valve 15, whereby the passage through valve I from port 1 to port 2 remains open. The pressure change by pressure control valve 15 is relatively slow, so for example, a rapid pressure drop cannot be achieved. During the exhaust phase, the passage from port 1 to port 2 is closed, while the passage from port 2 to port 3 is opened in order to discharge process exhaust gas through exhaust pipeline 12. The exhaust gas is led out through a silencer 13 to reduce noise. When the process air is switched by a single valve I, it may be necessary to branch pipeline 11 for supplying the process air to the injection molding die 10 to a plurality of connections on the injection molding die 10 ( Figure 1 in which are air inlets E1 and E2)( Figure 1 and which are provided with two branches). In this known device, fluctuations in the process air caused by changes in pressure and air flow time due to the pneumatic section with the pressure control valve may cause the molded part not to be ejected from the injection molding die 10 in the expected manner, and thus to fall off in different ways. In addition, suitable (proportional) pressure control valves are expensive, require variable control signals, and are less reliable than simple valves that can only be opened or closed.

[0049] In order to eliminate these drawbacks and to eliminate or at least improve the scatter in air control (related to the pressure of the process air and the control time of the pneumatic valve) and the associated unpredictable behavior in order to avoid process disturbances, an embodiment of a device according to the invention for providing process air at different pressures for more reliable demolding in an injection molding machine is described below.

[0050] For example, Figure 2 A schematic diagram (in the form of a pneumatic circuit or pneumatic circuit diagram) of a device 100 according to the invention for providing process air for demolding molded parts in an injection molding machine (with a plurality of optional features) is shown. Device 100 includes two valve pairs Ia, IIa and Ib, IIb, one of which is optional. The core of the invention isFigure 2 in the series configuration shown and the two valves are interconnected in pairs respectively, where each valve Ia, IIa (or Ib, IIb) in the valve pair is connected to its respective compressed air source (or process air source) pI, pII. The pressures of the two compressed air sources pI and pII are different, and thus they are preset (i.e., before the process starts) and then remain fixed (i.e., substantially constant). For example, the blowing pressure of the blowing air source pI for blowing the molded part out of the injection molding die is (significantly) lower than the pre-blowing pressure of the pre-blowing air source pII for tilting the molded part. At the pre-blowing pressure, the vacuum between the core of the injection molding die and the molded part is broken, and the molded part is separated from the surface of the injection molding die. It should be noted here that the release process (and the ejection process) is usually supported by a mechanical ejector. Thus, the main function of blowing is to space the molded part from the injection molding die in a desired manner, thereby enabling the molded part to safely fall off the injection molding die without touching other parts of the injection molding die. Properly setting and maintaining the blowing pressure is particularly important for an injection molding die having a large number of cavities (configured one above the other in rows (or adjacent to each other in columns) for simultaneous molding of many molded parts). In this case, it is important that the blowing air from the lower cavities does not touch the molded parts falling from the higher cavities. For example, it does not press them against the opposite side of the injection molding die. However, for specific applications, it is also considered (in advance) to set the blowing pressure higher than the pre-blowing pressure.

[0051] In Figure 2 it, the pressure source pII connected to the lower valve IIa is the pre-blowing air source (for providing the pre-blowing pressure), and the pressure source pI connected to the upper valve Ia is the blowing air source (for providing the blowing pressure). Therefore, the present inventor refers to the lower valve IIa as the pre-blowing valve and the upper valve Ia as the blowing valve. However, the upper pressure source pI can also be the pre-blowing air source, and the lower pressure source pII is the blowing air source. Thus, the upper valve Ia is also the pre-blowing valve, and the lower valve IIa is the blowing valve. It is usually advantageous that, as Figure 2 shown, the blowing valve Ia is connected downstream of the pre-blowing valve IIa because the pre-blowing pressure is usually (far) higher than the blowing pressure, and there will be a certain pressure drop when the process air flows through each valve. Since the flow rate through the two valves Ia, IIa during pre-blowing is very small, the pressure drop is also very small. The blowing air only flows through the blowing valve, which means the pressure drop is also smaller.

[0052] The two valves are basically identical, except that the upper valve Ia is directly connected to the air duct 11a that conveys process air to the injection molding die 10, while the lower valve IIa can be indirectly connected to the air duct 11a via the upper valve Ia. Conversely, the lower valve IIa is directly connected to the exhaust pipeline 12, and the upper valve Ia can be indirectly connected to the exhaust pipeline 12 via the lower valve IIa. Preferably, bistable valves should be used. In terms of signal technology, the valves used are usually monostable, but are controlled by an electro-pneumatic pilot, whereby the main spool of each valve is pressed into a defined end position, causing the valve to operate in a bistable manner. This ensures that the pre-blowing air from the pre-blowing valve flows through the blowing valve in a process-safe manner.

[0053] Both valves Ia and IIa are generally designed as 3 / 2-way valves, which have a first connection portion 1 for connecting to a supply pipeline (connected to the pressure sources pI, pII), a second connection portion 2 for connecting to a working pipeline (connected to the injection molding die 10), and a third connection portion 3 for connecting to the exhaust port of the working pipeline (connected to the exhaust pipeline 12).

[0054] According to the present invention, after the injection process, especially during the cooling phase of the molded part, the following process steps for demolding the molded part from the injection molding die 10 are performed. First, the air duct 11a is pressurized with pre-blowing air pressure from the pre-blowing air source pII. For this purpose, the passage from port 1 to port 2 in the pre-blowing valve IIa must be opened, and the passage from port 3 to port 2 in the downstream blowing valve Ia must also be opened. If both valves are so-called "normally closed" valves that can be electrically controlled (i.e., closed in the basic position - as Figure 2shown) or a so-called "normally open" valve (i.e., open in the basic position), the valve control unit will control the (lower) pre-blowing valve IIa in a different manner than the (upper) blowing valve Ia, because in the case of the blowing valve Ia, the passage from port 1 to port 2 must be closed when the passage from port 3 to port 2 is open, and in the case of the pre-blowing valve IIa, the passage from port 1 to port 2 must be open when the passage from port 3 to port 2 is closed. By closing the passage from port 1 to port 2 at the blowing valve Ia, the blowing source pI is not connected to the pipeline 11a, and thus not connected to the injection molding die 10 either. On the other hand, by opening the passage from connection part 1 to connection part 2 at the pre-blowing valve IIa, the pre-blowing source pII is indirectly connected to the air pipeline 11a via the open passage from connection part 3 to connection part 2 at the blowing valve Ia, and thus connected to the injection molding die 10, so there is pre-blowing pressure here. Since the pre-blowing is introduced into the injection molding die 10 at the pre-blowing pressure (which occurs between the molded part and the corresponding core of the injection molding die 10 when the injection molding die 10 is closed), the molded part (especially an open hollow body, such as the base of a rotator or a cup-shaped molded part) bulges, and the vacuum or negative pressure between the corresponding molded part and the core is destroyed. Therefore, after the pre-blowing is supplied for a certain period of time, the molded part is separated from the injection molding die 10.

[0055] Once the desired duration of the pre-blowing supply ends, the passage from connection part 1 to connection part 2 at the pre-blowing valve IIa is closed again by appropriate control of the pre-blowing valve IIa, so that the pre-blowing source pII is disconnected from the pipeline 11a. By closing the passage from port 1 to port 2 at the pre-blowing valve IIa, the passage from port 2 to port 3 at the pre-blowing valve IIa (automatically) opens, which allows the process exhaust gas to be discharged from the injection molding die 10 into the exhaust pipeline 12 via the air pipeline 11a and the open passage from port 2 to port 3 at the blowing valve Ia.

[0056] Then the air pipeline 11a is pressurized with the blowing pressure from the blowing source pI. For this purpose, the passage from port 1 to port 2 in the blowing valve Ia must be opened, while the passage from port 1 to port 2 in the upstream pre-blowing valve IIa is closed (this is the case when the passage from port 2 to port 3 in the pre-blowing valve IIa is open), so as to connect the blowing source pI to the injection molding die 10 at the blowing pressure, in order to introduce the blowing into the injection molding die 10 (especially into the interior of the molded part with an open hollow body), so as to blow the molded part out of the injection molding die 10 or space the molded part apart from the injection molding die 10 (usually assisted or even mainly achieved by a mechanical ejector).

[0057] After the desired time has elapsed since the molded part has been blown by the blowing supply unit, the passage from port 1 to port 2 at the blowing valve Ia is closed again by appropriate control of the blowing valve Ia, so that the blowing air source pI is separated from the pipe 11a. Closing the passage from port 1 to port 2 at the blowing valve Ia causes the passage from port 2 to port 3 at the blowing valve Ia to open (automatically), which allows the process exhaust gas to be discharged into the exhaust pipeline 12 from the injection molding die 10 via the air pipe 11a and the open passage from port 2 to port 3 at the pre-blowing valve IIa.

[0058] The separation of the molded part from the surface of the injection molding die 10 and the blowing out or ejection of the molded part from the injection molding die 10 can additionally be supported by actuating a mechanical ejector (either or both of separation and blowing out / ejection).

[0059] In addition, a compressed air reservoir 16 can also be used to support the blowing pressure, which is connected to the blowing supply pipeline of the connection 1 from the blowing air source pI to the blowing valve Ia. This reduces the sharp pressure drop during actuation of the blowing valve Ia and stabilizes the air flow by disconnecting the supplied blowing supply pipeline.

[0060] In addition, when the pre-blowing valve IIa is shut off, an (adjustable) spring pressure can be generated in the exhaust pipeline 12 by means of a check valve 17, which reduces the consumption of process air and prevents the air pipe 11a from being completely emptied via the exhaust pipeline 12. In addition, even after the pre-blowing valve IIa has been closed, the pre-tightening pressure set on the check valve 17 can (intentionally) extend the duration of the release process.

[0061] In the case of a large injection molding die 10, for example, in order to be able to simultaneously produce a large number of open hollow bodies having a large number of cavities (these cavities are arranged adjacent to each other in columns or one above the other in rows), such as rotary bodies or cup-shaped molded parts (such as bottle caps), it may be necessary to use multiple air pipes 11a, 11b for introducing process air into the injection molding die 10. Instead of branching only one air pipe (multiple times) and connecting it to multiple connections E1, E2 on the injection molding die 10, it is possible to advantageously use multiple independent air pipes 11a, 11b to improve the process air supply. As Figure 2As shown, each of the air ducts 11a, 11b can be associated with its respective valve pair Ia+IIa, Ib+IIb. The first valve pair consisting of the blowing valve Ia and the upstream pre-blowing valve IIa operates the first air duct 11a. The second valve pair in a parallel configuration consisting of the blowing valve Ib and the upstream pre-blowing valve IIb operates the second air duct 11b. The two pre-blowing valves IIa, IIb are connected to a common pre-blow air source pII, while the two blowing valves Ia, Ib are connected to a common blowing air source pI. Both air ducts 11a and 11b are exhausted via a common exhaust pipeline 12, which can of course also be done via two independent exhaust pipelines. The two valve pairs Ia+IIa and Ib+IIb are actuated in the same way, whereby the switching operation must be coordinated in detail according to the dimensions of the injection molding die 10 to achieve the desired demolding sequence. For example, if a large injection molding die has ten process air connection parts, ten parallel valve pairs can be used to optimize the process air supply. It should also be noted that smaller valves are more cost-effective and more dynamic (faster).

[0062] Other valves can also be introduced between the first valve of the valve pair in a series configuration and the upstream second valve to connect a third process air source supplying a different third pressure. In this way, other (fourth, fifth, etc.) process air sources can also be connected and used in the demolding process.

[0063] Explanation of Reference Numerals

[0064] 1 First valve connection for supply pipeline

[0065] 2 Second valve connection for working pipeline

[0066] 3 Third valve connection for exhausting (of working pipeline)

[0067] 10 Injection molding die

[0068] 11 (Air) duct from valve to injection molding die (with two air inlets into the injection molding die)

[0069] 11a (Air) duct from valve Ia to injection molding die (with the first air inlet into the injection molding die)

[0070] 11b (Air) duct from valve Ib to injection molding die (with the second air inlet into the injection molding die)

[0071] 12 Exhaust / exhaust pipeline

[0072] 13 Muffler

[0073] 14 Electrical control of valve

[0074] 15 Adjustable pressure control valve

[0075] 16 Compressed air storage

[0076] 17 Check valve (spring-loaded, e.g., with adjustable pre-tension force)

[0077] 100 Equipment for supplying process air

[0078] E1, E2 Lead to the air inlets in the injection molding die

[0079] Ea, Eb Lead to the air inlets in the injection molding die

[0080] I Valve, 3 / 2-way valve for supplying air and blowing (electrically actuated)

[0081] Ia Valve, the first valve for a, 3 / 2-way valve for blowing (electrically actuated)

[0082] IIa Valve, the second valve for a, 3 / 2-way valve for supplying air (electrically actuated)

[0083] Ib Valve, the first valve for b, 3 / 2-way valve for blowing (electrically actuated)

[0084] IIb Valve, the second valve for b, 3 / 2-way valve for supplying air (electrically actuated)

[0085] p Pressure (air) source with a fixed (air) pressure

[0086] pI Pressure (air) source with a first fixed (air) pressure

[0087] pII Pressure (air) source with a second fixed (air) pressure ≠ the first (air) pressure

Claims

1. An apparatus (100) for an injection molding machine having an injection molding die (10), for providing process air at a first pressure and at a second pressure different from the first pressure, characterized in that, The device (100) has a series configuration of two valves (Ia, IIa; Ib, IIb), where the first valve (Ia; Ib) is connected on the one hand to a first pressure source (pI) having the first pressure and on the other hand to a duct (11a; 11b) that leads into the injection molding die (10), and the second valve (IIa; IIb) is connected to a second pressure source (pII) having the second pressure and to an exhaust line (12), wherein the first valve (Ia; Ib) and the second valve (IIa; IIb) are designed and can be actuated such that the duct (11a; 11b) can withstand the first pressure or the second pressure.

2. The device (100) according to claim 1, characterized in that, The two valves (Ia, IIa; Ib, IIb) are 3 / 2-way valves, each 3 / 2-way valve having a first connection (1) for connection to a supply line, a second connection (2) for connection to a working line, and a third connection (3) for connection to an exhaust port of the working line, wherein the first connection (1) of the first valve (Ia, Ib) is connected to the first pressure source (pI), the second connection (2) of the first valve (Ia; Ib) is connected to the duct (11a; 11b), and the third connection (3) of the first valve (Ia; Ib) is connected to the second connection (2) of the second valve (IIa; IIb), and wherein the first connection (1) of the second valve (IIa; IIb) is connected to the second pressure source (pII), and the third connection (3) of the second valve (IIa; IIb) is connected to the exhaust line (12) for discharging process air.

3. The device (100) according to any one of claims 1 or 2, characterized in that, Two or more series configurations of the two valves (Ia, IIa; Ib, IIb) of the valve pairs are connected in parallel, each of the first valves (Ia; Ib) of the valve pairs being connected respectively to the first pressure source (pI), and each of the second valves (IIa; IIb) of the valve pairs being connected respectively to the second pressure source (pII) and in particular to the exhaust line (12), and each of the first valves (Ia; Ib) of the valve pairs being connected in particular via independent ducts (11a; 11b) to the injection molding die (10).

4. The device (100) according to any one of claims 1 to 3, characterized in that, Other valves are inserted in series between the first valve (Ia; Ib) and the second valve (IIa; IIb), wherein the other valves are connected to other pressure sources having other pressures different from the first pressure and the second pressure, wherein the first valve (Ia; Ib), the second valve (IIa; IIb) and the other valves are designed and controllable such that the pipelines (11a; 11b) can all withstand the first pressure, the second pressure or the other pressure, wherein the other valves are in particular 3 / 2-way valves, wherein in particular the first connection part of the other valve is connected to the other pressure source, the second connection part of the other valve is connected to the third connection part (3) of the first valve (Ia; Ib), and the third connection part of the other valve is connected to the second connection part (2) of the second valve (IIa; IIb).

5. The device (100) according to any one of claims 1 to 4, characterized in that, The first pressure and / or the second pressure and / or possibly the other pressure is adjustable.

6. The device (100) according to any one of claims 1 to 5, characterized in that, The valves (Ia, IIa; Ib, IIb) are electrically controllable, in particular the valves (Ia, IIa; Ib, IIb) are solenoid valves.

7. The device (100) according to any one of claims 1 to 6 further comprises a control unit, which is designed to activate only one of the first valve (Ia; Ib), the second valve (IIa; IIb) and optionally the other valves each time, so as to pressurize the pipeline (11a; 11b) with the first pressure or the second pressure or optionally the other pressure.

8. The device (100) according to any one of claims 1 to 7 further comprises a compressed air storage (16), which is connected to the first pressure source (pI) or the second pressure source (pII) and the first port (1) of the first valve (Ia; Ib) or the second valve (IIa; IIb), in particular the first valve (Ia; Ib) or the second valve (IIa; IIb).

9. The device (100) according to any one of claims 1 to 8 further comprises a check valve (17) arranged in the exhaust pipeline (12), in particular further comprises a silencer arranged in the exhaust pipeline (12), wherein the check valve (17) is arranged between the second valve (IIa; IIb) and the silencer, wherein in particular the pre-tightening force of the check valve (17) is adjustable.

10. An injection molding machine, which has an injection molding die (10) and the device (100) according to any one of claims 1 to 9, wherein the device (100) is connected to the injection molding die (100) via one or more pipelines (11a, 11b) so as to be able to introduce process air into the injection molding die (10) at at least two different pressures.

11. The injection molding machine according to claim 10 further comprises one or more mechanical ejectors, for example in the form of a stripping ring, which are designed to separate the molded part from the injection molding die (10) or from the surface of the injection molding die (10), and / or to eject the molded part from the injection molding die to support the demolding process of the molded part.

12. The injection molding machine according to claim 10 or 11 is designed to produce open hollow bodies, such as rotary bodies or cup-shaped molded parts, in particular in order to produce a plurality of such molded parts simultaneously, wherein the injection molding die (10) in particular has a plurality of cavities for shaping the molded parts, and the plurality of cavities are arranged in columns adjacent to each other or in rows one above the other.

13. A method for demolding a molded part from an injection molding die (10) in an injection molding machine according to any one of claims 10 to 12 by means of a device (100) according to any one of claims 1 to 9, the molded part being in particular an open hollow body, such as a rotary body or a cup-shaped molded part, for example a bottle cap, the method comprising the following steps after the injection process, in particular during the cooling phase of the molded part in the injection molding die (10) of the injection molding machine: - Applying a pre-blowing pressure to the pipe (11a; 11b) by opening the passage in the pre-blowing valve connecting the pre-blowing gas source to the pipe (11a; 11b) and by closing the passage in the blowing valve connecting the blowing pressure source to the pipe (11a; 11b), in particular in order to introduce the pre-blowing gas into the injection molding die (10) at the pre-blowing pressure, in particular between each molded part and the core of the injection molding die (10) when the injection molding die (10) is closed, in particular in order to curl each molded part, in particular in order to break the vacuum between each molded part and the core, so that the molded part is separated from the injection molding die (10); - Applying a blowing pressure to the pipe (11a; 11b) by opening the passage in the blowing valve connecting the blowing pressure source to the pipe (11a; 11b) and by closing the passage in the pre-blowing valve connecting the pre-blowing pressure source to the pipe (11a; 11b), in particular in order to introduce the blowing gas into the injection molding die (10) at the blowing pressure, in particular into the interior of the open hollow body, such as a rotary body or a cup-shaped molded part, in order to blow the molded part out of the injection molding die (10); - Venting the injection molding die (10) by closing the passage in the blowing valve connecting the blowing pressure source to the pipe (11a; 11b) and by opening the respective passages in the pre-blowing valve and the blowing valve connecting the pipe (11a; 11b) to the exhaust pipeline (12). Wherein the pre-blowing pressure is one of the second pressure and the first pressure in the device (100), and conversely the blowing pressure is the other of the first pressure and the second pressure in the device (100), and thus, the pre-blowing gas source is one of the second pressure source (pII) and the first pressure source (pI) in the device (100), and conversely the blowing gas source is the other of the first pressure source (pI) and the second pressure source (pII) in the device (100), and wherein the pre-blowing valve is one of the second valve (IIa; IIb) and the first valve (Ia; Ib) in the device (100), and conversely, the blowing valve is the other of the first valve (Ia; Ib) and the second valve (IIa; IIb) in the device (100).

14. The method according to claim 13, performed using the injection molding machine according to claim 11, comprising at least one of the following two additional steps: - Actuating a mechanical ejector to support the demolding process, in particular during or after applying the pre-blowing pressure to the pipe (11a; 11b), in order to separate the molded part from the injection molding die (10) or from the surface of the injection molding die (10); - Actuating a mechanical ejector to support the demolding process, in particular before or during applying the blowing pressure to the pipe (11a; 11b), in order to eject the molded part from the injection molding die (10).

15. The method according to claim 13 or 14, comprising the following additional step: - Supporting the blowing pressure via a compressed air reservoir (16) in order to reduce the sharp pressure drop during actuation of the blowing valve and to stabilize the air flow by disconnecting the supplied blowing pipeline.

16. The method according to any one of claims 13 to 15, comprising the following additional step: - Generating a spring pressure in the exhaust pipeline (12) by means of a check valve (17) when the pre-blowing valve is closed, in order to reduce the consumption of process air and to prevent complete evacuation of the pipe (11a; 11b) via the exhaust pipeline (12).

17. Use of the device (100) according to any one of claims 1 to 9 for demolding a molded part from an injection molding die (10) during production using an injection molding machine, the molded part in particular being an open hollow body, such as a rotating body or a cup-shaped molded part, for example a bottle cap.

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