Patent Application
20230264846
This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to German patent application number DE 10 2022 104 218.9, filed Feb. 23, 2022, which is incorporated by reference in its entirety.
The disclosure relates to a thermoforming packaging machine and to a method for operating a thermoforming packaging machine.
In thermoforming packaging machines, a trough is usually formed in a lower film in a forming station, a product is inserted into it and the trough is sealed in an airtight manner with an upper film under vacuum and/or modified atmosphere in a sealing station. The packages thus produced are attached to each other as a composite via the lower film and are transported through the thermoforming packaging machine by clamp chains mounted on both sides. A combination of a transverse cutting station and a subsequent longitudinal cutting station can be provided for separating the packages from the composite of the lower and upper film. In the transverse cutting station, the composite of the lower and upper film is cut transversely to the transport direction or, if radii are required at the edges of the packages, strip cuts or so-called star cuts are cut out. In this context, as disclosed for example in EP 3 088 315 A1, the knife can punch out the cutting waste coming from above and the cutting waste falls downwards. If there is not enough space for a system for collecting inside the machine frame or for transporting out of the machine frame, the punching knife can punch out the cutting waste coming from downwards to the top. These are then pushed further upwards in a receiving container after each cut and can then be removed collectively. In high-performance machines, the receiving containers are very tall so that they do not have to be continuously emptied. In this process, the cutting waste is pushed over a shoulder which is located above a film transport plane and on which the last cut cutting waste partially rests with its edge, and thus, it is to be prevented that the cutting waste stacked above it falls downwards into the transverse cutting station or onto the packages to be cut. In the latter case, malfunctions would occur in the thermoforming packaging machine. Especially in the case of thinner or non flexurally-rigid cutting waste, there is a high risk that the weight of the stacked cutting waste cannot be held by the lowest resting cutting waste. A solution to this problem is proposed in EP 2 447 171 B1. By means of a pusher in the transverse cutting station, some of the punching waste is safely carried. This is particularly achieved in the case of strip cuts, but not reliably in the case of star cuts. Another disadvantage is the mechanical configuration of the pusher, which on the one hand is complex and therefore cost-intensive to manufacture, and on the other hand is subject to wear and must be serviced regularly.
In order to remove different geometries of cutting waste, DE 10 2008 015 691 B3 proposes a solution in which the cutting waste is disposed of by means the use of powerful blowers and the routing of the cutting waste via so-called vacuum-suitable spiral hoses. These hoses are on the one hand difficult to clean due to their groove-shaped surface and are therefore undesirable in the food sector, and on the other hand, strip cuts in particular can get caught in these hoses due to their geometry and lead to clogging of the hose. In order to remove the clogging, the operator has to switch off the machine, remove the hose and clean it by hand. This leads to undesired downtime of the entire system.
An objective of the present disclosure is to provide a device which safely disposes of different cutting waste, such as strip cuts and star cuts, as well as different film types, such as thin, flexurally-rigid films, and thick films. In addition, it is an objective of the present disclosure to provide a wear-free and low-maintenance device, as well as a reliable device with low operating costs. Moreover, it is an objective of the present disclosure to provide a method for the operation of this device.
These objectives may be addressed by a thermoforming packaging machine according to the disclosure, or by a method for its operation.
The thermoforming packaging machine according to the disclosure comprises at least one transverse cutting station, wherein the transverse cutting station comprises a punching device for cutting out one or more film sections from a lower film and/or an upper film by means of a punching tool comprising a punch and a die. In this context, the punching device has a chamber which is configured to receive, at least temporarily, the film sections, and a suction device for conveying film sections out of the transverse cutting station, wherein the suction device is fluidically connected to a compressed gas source. Film sections are sections separated from the lower and/or upper film, which are also generally referred to as cutting waste. These can be so-called strip cuts, star cuts, Euro holes or other sections with geometries.
In a preferred variant of the thermoforming packaging machine according to the disclosure, the suction device is configured as a volume booster into which a compressed gas can be injected by means of a compressed gas source. In a particularly preferred embodiment of the thermoforming packaging machine according to the disclosure, the compressed gas can be injected through an annular gap. In this context, a volume booster is understood to be a pipe arrangement comprising a first and a second pipe, which are arranged coaxially to one another and form a suction channel. The suction channel has an intake side and an outlet side. Between the intake and outlet sides, the pipe arrangement has a thin annular gap through which a gas is introduced at very high velocity. This causes a negative pressure at the intake side of the volume booster and thus entrains gas, for example ambient air, so that an increased volume flow exits at the outlet side. An annular gap can be regarded as an opening or a plurality of openings extending circumferentially around the suction channel. In addition, it is preferred if a pressure regulator is used between the compressed gas source and the suction device in order to be able to set a desired pressure at the suction device. This can serve to limit the pressure applied to the suction device, thereby limiting the operating costs of the suction device and minimizing unwanted noise emissions.
It is particularly preferred if the punching device has a hood forming the chamber, wherein the chamber has at least two openings. It can also be useful if the hood is removably mounted on the punching device in order to be able to easily remove any clogging of the chamber caused by the punching waste by removing the hood.
In a further embodiment of the disclosure, it is conceivable that the first opening is formed by the die. During the cutting process, the punch enters the die to cut or punch out the film. In doing so, the punch almost completely closes the opening of the die. The opening of the die is released again when the punching process is completed and the punch has moved out of the die again. The movement of the punch is often realized via a pneumatic drive. For this, a constant and high pressure is required by the compressed gas source to generate the necessary forces for the cutting process. If several compressed gas consumers are activated at the same time, the pressure of the compressed gas supply may fluctuate depending on the reliability of the compressed gas source. It is therefore expedient that the volume flow generated by the suction device for conveying film sections out of the transverse cutting station is interrupted during the cutting process.
It is preferred that the suction device forms the second opening of the chamber.
The openings are an exit opening through which the film sections are discharged from the chamber and an opening which is configured to ventilate the chamber. It is preferred in this embodiment of the present disclosure that the volume flow generated by the suction device flows from the die through the chamber and through the suction device itself. Thus, the generated cutting waste is reliably conveyed out of the punching device.
It is particularly preferred if the ratio of the cross-section of the chamber, viewed parallel to the transport direction, to the cross-section of the suction device is between 0.5 and 1.5, preferably between 0.5 and 1.2, especially preferably between 0.5 and 1. The ratio of the cross-sections of the suction device and the chamber influences the flow rate of the volume flow. The larger the cross-section of the chamber compared to the cross-section of the suction device, the lower the flow rate within the chamber. It is preferred to achieve a high flow rate in the chamber. It is particularly preferred if the flow rate in the suction device is slightly greater than in the chamber.
In a further development of the disclosure, it is conceivable that a compressed gas connection is present at the end of the chamber opposite the suction device and/or a further opening is present, the opening cross-section of which is preferably adjustable. If film sections are in the form of strip cuts, it is possible that these are only lifted on one side during suction and therefore remain stuck in the die. It may occur that the strip cuts are first lifted out of the die on the side facing the suction device. As a result, a large part of the volume flow is directed at this point. On the side of the die facing away from the suction device, the volume flow may then no longer be sufficient to convey the strip cuts out of the die. Due to the hook shape of the strip cuts, they do not detach from the die in such a case. It is therefore preferred to provide a compressed gas connection on the side of the chamber facing away from the suction device. The discharge of strip cuts can thus be ensured via a volume flow from this compressed gas connection. The further opening can also be formed by an area with a plurality of small openings, such as a grid or a perforated plate. The volume flow can be influenced by adjusting the opening cross-section of this additional opening. A small opening cross-section results in a larger proportion of the volume flow passing through the die and a smaller proportion of the volume flow passing through the additional opening—and vice versa.
One embodiment of the disclosure provides that a deflection device is attached to the suction device, which is configured to direct film sections into a collecting container. Thus, film sections can be conveyed directly out of the transverse cutting station without having to be guided through a hose. On this short path, which the film sections cover during transport, the risk of film sections getting caught and causing clogging is greatly reduced. In addition, the suction device is easy to inspect and, should a clogging occur, easy to clean.
The disclosure also comprises a method of operating a thermoforming packaging machine. The device according to the disclosure is suitable, adapted and configured for carrying out the method. Features described with respect to the device can be transferred to the method and vice versa.
A method according to the disclosure for operating a thermoforming packaging machine comprises a control system and at least one transverse cutting station. The transverse cutting station comprises a punching device for cutting out one or more film sections from a lower film and/or an upper film by means of a punching tool comprising a punch and a die. For this purpose, the method comprises the following steps: at least one film section is cut out of the lower film and/or the upper film by means of the punching tool, the at least one film section is at least temporarily received in a chamber of the punching device, and a volume flow is generated by means of a compressed gas source to convey the at least one film section out of the chamber of the transverse cutting station.
Preferably, an opening of the chamber is released in the method by guiding the punch out of the die. This allows the volume flow generated by the suction device to be directed through the die and thus specifically supports the conveying out of the cutting waste.
In one conceivable embodiment, the volume flow is generated by means of a volume booster by blowing gas, in particular compressed air, into a suction device.
It is particularly convenient if the film section is conveyed through the volume booster.
In a further development of the method, the generation of the volume flow by means of the control system is interrupted at least for the duration of the punching process.
Furthermore, it is preferred if a further volume flow is generated in the method by injecting gas, in particular compressed air, into the chamber.
In a particularly preferred further development of the method, the frequency, duration and/or intensity of the volume flow and/or the further volume flow can be adjusted on the basis of an input by an operator at a man-machine interface and is communicated by means of the man-machine interface to a control system of the thermoforming packaging machine.
In the following, an embodiment of the disclosure is described in more detail with reference to a drawing.
As those skilled in the art will understand, the man-machine interface 17, the control system 18, as well as any other controller, unit, system, subsystem, interface, sensor, device, or the like described herein may individually, collectively, or in any combination comprise appropriate circuitry, such as one or more appropriately programmed processors (e.g., one or more microprocessors including central processing units (CPU)) and associated memory, which may include stored operating system software, firmware, and/or application software executable by the processor(s) for controlling operation thereof and for performing the particular algorithm or algorithms represented by the various methods, functions and/or operations described herein, including interaction between and/or cooperation with each other. One or more of such processors, as well as other circuitry and/or hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC) or Electronic Control Unit (ECU), or several processors and various circuitry and/or hardware may be distributed among several separate components, whether individually packaged or assembled into a System-on-a-Chip (SoC).
| Number | Date | Country | Kind |
|---|---|---|---|
| 102022104218.9 | Feb 2022 | DE | national |
