This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to German patent application number DE 102021110382.7, filed Apr. 23, 2021, which is incorporated by reference in its entirety.
The present disclosure relates to a sealing station.
Such a sealing station is known from DE 10 2012 006 696 A1 and DE 10 2018 114 263 A1. The product protection plates used within these sealing stations, which are arranged on the lower side of a sealing plate, have the function of reducing the heat emitted by the sealing plate onto the product placed in deep-drawing troughs or packaging trays.
It is known to fasten product protection plates from below by means of countersunk screws to the sealing plate positioned thereabove. During operation of the sealing station, the screw heads positioned on the lower side of the product protection plate can heat up. This can lead to the formation of visually undesirable marks on the top film of the sealed packages as a result of the sealing process. In order to alleviate this problem, in practice the screw heads facing the top film are covered with a silicone. However, the silicone cannot completely prevent marks from being left on the top film.
In addition, product protection plates are detachably fastened to the sealing plate for cleaning or maintenance work, so that silicone applied over the screw head makes it difficult to install and dismantle a product protection plate. On the one hand, this is due to the fact that the silicone must first be scraped off in a time-consuming process in order to dismantle the product protection plate. On the other hand, a new silicone must be applied after the product protection plate has been reinstalled. The associated curing time extends the downtime of the tool, which leads to increased idle times of the packaging machine.
The use of temperature-resistant screws made of plastic can also leave marks on top films. Screwing the product protection plates on the side facing away from the top film significantly increases the installation and service effort. It has also been found that sinking the countersunk screws into recessed bores formed on the lower side of the product protection plate still allows the product protection plate to be installed and dismounted from the front, however these bores can also leave marks on the top film. A further problem with such bores is that product residues can accumulate in them, which impairs hygienic standards.
In view of the problems described in connection with the prior art, it is an object of the disclosure to provide a sealing station with a product protection plate, by means of which it is possible to produce packaging which is flawless, particularly from the optical point of view.
The disclosure relates to a sealing station for a packaging machine, which is provided in particular in the form of a deep-drawing packaging machine or in the form of a tray-sealing machine. The sealing station according to the disclosure has a sealing tool lower part for receiving deep-drawing troughs or packaging trays and a sealing tool upper part positioned above it with at least one heatable sealing plate. The sealing plate is configured to seal the deep-drawing troughs or packaging trays received by the sealing tool lower part with an upper film, wherein at least one product protection plate is fastened to a lower side of the sealing plate. Its function is to reduce heat transfer from the sealing plate to the product to be packaged. The sealing tool upper part has at least one fastening mechanism for detachably fastening the product protection plate to the lower side of the sealing plate. This allows the product protection plate to be dismantled for service or cleaning purposes, for example.
According to the disclosure, the fastening mechanism between the sealing plate and the product protection plate comprises at least one magnetic locking unit for generating a magnetic holding force for fastening the product protection plate to the sealing plate, at least one hook-in locking unit for fastening opposite outer sides of the product protection plate to areas of the sealing plate facing them, or at least one gravity locking unit which is configured to lock the product protection plate to the sealing tool upper part by means of a gravitational force exerted by the product protection plate in the mounted state and pointing away from the sealing plate positioned above it.
The fact that the fastening means proposed in accordance with the disclosure are formed between the sealing plate and the product protection plate, i.e., on opposite sides thereof, means that the lower side of the product protection plate facing away from the sealing plate and towards the upper film remains free of mounting means and thus does not need to have any bores for such mounting means. Consequently, the lower side of the product protection plate can be provided with a flat surface that leaves no marks on the upper film.
The three above-mentioned alternatives for fastening the product protection plate according to the disclosure can be implemented easily and cost-effectively on the sealing station from a structural point of view. Furthermore, the respective alternatives enable the product protection plate to be installed and dismantled quickly and easily at the sealing station. Above all, however, it is possible to avoid marks on the top or lid film. Furthermore, the fastening alternatives according to the disclosure allow idle times of the sealing station to be reduced, since the product protection plate can be installed and dismantled at the sealing station without great effort, in particular within a short time.
Preferably, the magnetic locking unit has at least one permanent magnet that is fastened to the sealing plate or to the product protection plate. The permanent magnet could, for example, be fastened to a lower side of the sealing plate facing the product protection plate, in particular centrally above the product protection plate. Such a permanent magnet can be manufactured at low cost and can be integrated as a functional component in a compact manner at the sealing station.
It is conceivable that several permanent magnets are fastened to the lower side of the sealing plate, in particular according to an evenly distributed arrangement. This can bring technical assembly advantages for the product protection plate.
A preferred variant provides that the magnetic locking unit comprises at least one component made of a soft magnetic material (hereinafter also referred to as “soft magnetic component”), which is fastened to the sealing plate or the product protection plate. Provided that this component is fastened to the product protection plate, the permanent magnet is fastened to the sealing plate and vice versa. When the product protection plate is installed at the sealing station, the permanent magnet and the component made of a soft magnetic material may be positioned opposite each other to provide a desired holding force for fastening the product protection plate to the sealing plate.
It is conceivable that, in the assembled state of the product protection plate, the permanent magnet has a trough-like centering recess facing the soft magnetic component, in which at least part of the soft magnetic component is held in a form-fitting manner. The permanent magnet and the soft magnetic component together form a centering unit. The centering recess can be oval-shaped in particular. This allows the product protection plate to be fastened to the sealing plate in a manner that is stable in terms of position.
According to an embodiment of the disclosure, the permanent magnet and/or the component made of the soft magnetic material have at least a partial plastic coating. This enables a smooth and noise-reduced installation and dismantling of the product protection plate at the sealing station.
One variant provides for the permanent magnet and the component made of the soft magnetic material to be fully embedded in plastic. This full coating has the advantage that manufacturing tolerances can be better compensated and prevents mechanical stresses in the magnetic components.
A preferred variant provides that the permanent magnet or the component made of the soft magnetic material is fastened inside a recess formed on the sealing plate. This favors a flat assembly of the sealing plate and the product protection plate. In this way, if necessary, shortened stroke cycles can be achieved during operation of the sealing station.
It is conceivable that in the assembled state the soft magnetic component is fastened by screwing to an upper side of the product protection plate facing the sealing plate, wherein a part of the soft magnetic component projecting from the upper side of the product protection plate forms a negative shape to the centering recess formed in the permanent magnet. Their respective shapes can be non-rotatable relative to each other. Thus, it is possible for the permanent magnet together with the soft magnetic component to form a centering unit to fasten the product protection plate to the sealing plate in a predetermined position and alignment.
Preferably, the sealing plate forms a receptacle on its lower side shaped to receive the product protection plate. In the assembled state, this results in a flat, cassette-like module.
According to a preferred variant, the hook-in locking unit has at least one hook-in projection formed on a first outer side of the product protection plate and at least one elastic locking bracket arranged on a second outer side of the product protection plate opposite the first. The fastening means displaced to opposite outer sides of the product protection plate allow easy installation and dismantling of the product protection plate at the sealing station. The hook-in projection can be hooked within an indentation of the sealing plate. The locking bracket can lock onto a projection of the sealing plate.
According to an embodiment, the hook-in projection is integrally formed on the product protection plate, i.e., integrally formed therewith. In particular, the elastic locking bracket can be screwed to the product protection plate on its upper side facing the sealing plate.
Preferably, the locking bracket has a locking tongue that can engage the projection formed on the sealing plate to secure the hooked product protection plate to the sealing plate. It is conceivable that the elastic locking bracket can be released from a state locked to the sealing plate by means of a screwdriver so that the product protection plate can be easily dismantled from the sealing station by an operator, for example for service, cleaning and/or conversion measures.
In the two variants of the locking mechanism described above, i.e., the magnetic locking unit and the hook-in locking unit, it would be possible for at least one spacer to be positioned between the sealing plate and the product protection plate in the assembled state. Preferably, the spacer is arranged on the sealing plate within the receptacle formed thereon for receiving the product protection plate, for example screwed securely therein. A preferred variant provides a total of four spacers distributed within the mounting recess around the permanent magnet fixed therein.
A preferred embodiment provides that the gravity locking unit is configured to unlock the product protection plate in the dismantled state of the sealing tool upper part, when the latter is turned upside down, by merely pushing the product protection plate in the direction of gravity. Such a gravity locking mechanism may be in the form of a push-to-open locking mechanism, wherein pressing in this variant may be facilitated by the gravitational force of the product protection plate to bring it into an unlocked state for detachment.
It is possible that the gravity locking unit has at least two ball-shaped locking bodies. It is conceivable that these two balls are received within guide bores formed on the sealing plate, which also form part of the gravity locking unit. These guide bores can be such that the two balls tend to move toward each other for locking the product protection plate and tend to move apart for unlocking the product protection plate. For this purpose, the guide bores can have a bore cross section that tapers towards the product protection plate.
One variant provides that the product protection plate has at least two centering bolts on its upper side and the sealing plate has two corresponding centering bores. The centering bolts make it easier to install and dismantle the product protection plate at the sealing station.
In an embodiment, the gravity locking unit has a bolt in the form of a countersunk screw fastened to the product protection plate, which can be inserted head first into a mounting opening formed on the sealing plate to secure the product protection plate to the sealing plate. The head shape formed on the bolt can be secured to the gravity locking unit by means of the two balls.
Preferably, the product protection plate has a lower side facing the sealing tool lower part in the assembled state with a surface free of bores. The flat surface thus facing the product prevents marks from forming on the lid film.
The disclosure further relates to a packaging machine which is in the form of a deep-drawing packaging machine or in the form of a tray-sealing machine (also known as a “tray-sealer” in specialist circles) and has a sealing station in accordance with the disclosure. On such a deep-drawing packaging machine, deep-drawing troughs can be sealed with an optically flawless lid film. The same applies to a tray sealer on which the sealing station according to the disclosure is used, in particular a product protection plate by means of the fastening mechanism according to the disclosure.
Preferred embodiments of the disclosure are explained in more detail below with reference to Figures. In detail:
Identical components are identified throughout the Figures by the same reference signs.
In the embodiment shown, the forming station 2 is configured as a deep-drawing station in which deep-drawing troughs T are formed into the lower film 8 by deep-drawing, for example by means of compressed air and/or vacuum. The forming station 2 can be configured such that several deep-drawing troughs T are formed next to one another in the direction perpendicular to the transport direction R. A filling path 12 is provided downstream of the forming station 2 in the transport direction R, in which the deep-drawing troughs T formed in the lower film 8 are filled with product.
The sealing station 3 has a hermetically sealable chamber 3a in which the atmosphere in the deep-drawing troughs T can be evacuated and/or replaced by gas purging with an exchange gas or a gas mixture before sealing with the upper film 10 dispensed from an upper film receptacle 9.
The transverse cutting device 4 can be configured as a die cutter which cuts the lower film 8 and the upper film 10 in a direction transverse to the transport direction R between adjacent deep-drawing troughs T. The upper film 10 and the lower film 8 are cut in the same direction. The transverse cutting device 4 operates in such a way that the lower film 8 is not cut across its entire width, but is not cut through at least in an edge region. This enables controlled onward transport through the transport chain 11.
The longitudinal cutting device 5 can be configured as a knife arrangement with which the lower film 8 and the upper film 10 are cut between adjacent deep-drawing troughs T and at the lateral edge of the lower film 8 in the transport direction R, so that separated packages are present downstream of the longitudinal cutting device 5.
The deep-drawing packaging machine 1 also has a control system 19, which has the task of controlling and monitoring the processes running in the deep-drawing packaging machine 1. A display device 20 with operating elements 21 is used to visualize or influence the process sequences in the deep-drawing packaging machine 1 for or by an operator.
The sealing tool upper part 17b of
Furthermore,
In
The component 27 made of the soft magnetic material forms an integral part of the product protection plate 23. In the assembled state, the product protection plate 23 shown in
The magnetic locking unit 24 shown in
By means of the hook-in locking unit 35 shown in
According to
The alternative fastening mechanisms for the product protection plate 23 described in advance in
Number | Date | Country | Kind |
---|---|---|---|
102021110382.7 | Apr 2021 | DE | national |