Device for thermally sealing a packaging container

Abstract

The invention relates to a device (10) for thermally sealing a packaging container with a vessel and a lid for a foodstuff, comprising a sealing element (11) and a pressure element (13) for pressing the lid onto the vessel, wherein the pressure element (13) can be pressed against the lid when the sealing element (11) is lifted off the lid.

Description

The invention relates to a device for the thermal sealing of a packaging container having a container and a lid for a food product, having a sealing element and a pressure element for pressing the lid onto the container.From the prior art, generic devices are known which are widely used for sealing a packaging container. The packaging container to be sealed has hitherto been provided with a plastic vessel and an aluminium foil for airtight sealing. After filling the plastic vessel with the foodstuff, the aluminum foil is applied to the plastic vessel in an airtight manner. The devices of the aforementioned type are not suitable, however, for sealing a packaging container with a plastic vessel and a plastic lid in an airtight manner after filling. This is because during the sealing process, the plastic container and the plastic lid melt in the sealing region, so that the sealing element remains adhered to the plastic lid when it is lifted from the packaging container. Consequently, the plastic lid with the sealing element is at least partially lifted off the plastic vessel and the airtight seal of the packaging container is destroyed.The invention has the object of improving a device of the type mentioned at the beginning to the effect that it can also be used to close a packaging container with a plastic vessel and a plastic lid in an airtight manner.The invention achieves the stated object with a device of the generic type in which, according to the invention, a pressure element can be pressed against the lid when a sealing element is lifted off a lid. In a first step, the pressure element can press the lid against a vessel. As soon as the pressure element abuts the lid, in a second step the sealing element can be applied to the lid in a sealing region for the sealing process. The sealing process can then follow as a third step in order to seal the vessel to the lid. After completion of the sealing process, the sealing element can be lifted off the lid in the fourth step. In this case, the pressure element advantageously continues to press against the cover. Thus, the lid connected to the vessel remains on the vessel without destroying the airtight seal between the vessel and the lid. Finally, in the last step, the pressure element can be lifted off the cover.The device is suitable in particular for a cohesive connection of the cover to the vessel. The material-to-material connection can be produced by a welding method, for example by a fusion welding method or an ultrasonic welding method. In the fusion welding method, the sealing member functions as a heating element. In the ultrasonic welding method, the sealing element constitutes a sonotrode. The device can also be used for bonding the vessel to the lid.So that the pressure element can reliably press against the lid when the sealing element is lifted off the lid, at least one spring element can be arranged between the sealing element and the pressure element, which is expediently a compression spring.The at least one spring element can be fixed by receiving elements at one end to the sealing element and at the other end to the pressure element. As a result, the at least one spring element is mounted in a fixed position with respect to the sealing element and the pressure element. In addition, the at least one spring element cannot buckle laterally when compressed.In order to be able to place the pressure element precisely at a specific location on the lid, the pressure element can be guided relative to the sealing element by guide elements. Guide elements that can be considered are, for example, guide bushes in which guide pins are guided linearly.The sealing element can have a closed, circumferential sealing surface. This makes it possible to ensure that the lid seals the vessel in an airtight manner along a closed circumferential opening edge of the vessel.For the sealing process, the sealing element is heated to a specific temperature, so that the lid, the vessel and a joining agent possibly provided between the lid and the vessel are heated in the region of the sealing surface and can melt as far as necessary. In order to prevent the lid from also melting in a contact region between the pressure element and the lid and, as a result, the lid remaining adhering to the pressure element when the sealing element is lifted off the packaging container, it is expedient to prevent or at least minimize a heat transfer from the sealing surface or from the sealing element to the pressure element. For this purpose, the pressure element can be made of a material that has a lower thermal conductivity than the material from which the sealing element is made.Likewise, the pressure element can be made of a material that has a lower heat capacity than the material from which the sealing element is made. Thus, the pressure element can absorb only little heat compared to the sealing element, which gives it off again in a short time. Consequently, the cover can only heat up somewhat at best.The lid can be cooled during the sealing process with various cooling media, preferably with water or air.For the same reasons mentioned above, the receiving elements and / or the guide elements can likewise be manufactured from a material which has a lower thermal conductivity than the material from which the sealing element is manufactured. Thus, the risk of unacceptable heating of the pressure element and consequently of the cover is reduced.Likewise, the receiving elements and / or the guide elements can also be manufactured from a material which has a lower heat capacity than the material from which the sealing element is manufactured.The receiving elements and / or the guide elements and / or the pressure element can be manufactured from a plastic. Preferably, a heat-resistant plastic is selected for this purpose, such as a PEEK, a PPS, a PES or another heat-resistant thermoplastic.In order to prevent adhesion of the lid to the sealing surface of the sealing element when the sealing element is lifted off the lid, the sealing surface can be equipped with an anti-stick coating.Because good thermal conductivity of the sealing element may be decisive for the success of the sealing process, the sealing element may be made of metal.An exemplary embodiment of the device according to the invention is explained in more detail below with reference to the attached drawing.In detail, the following show: FIG. 1 shows a perspective view from below of a sealing element; FIG. 2 shows a perspective view from above of the sealing element from FIG. 1 ; FIG. 3 shows a sectional view through the sealing element according to FIGS. 1 and 2 ; FIG. 4 shows a detailed view of the sectional view from FIG. 3 in the region of a sealing surface.FIGS. 1 to 3 show a device 10 for the thermal sealing of a packaging container, not shown in detail here, with a container and a lid for a food. The device 10 has a sealing element 11 with a sealing surface 12 running around the circumference in a closed manner and a pressure element 13 for pressing the lid onto the vessel (see also FIG. 4 ).Spring elements 14 are mounted between the sealing element 11 and the pressure element 13. The spring elements 14 are designed as compression springs. As a result, when the sealing element 11 is lifted off the lid, the pressure element 13 can reliably press against the lid, so that the lid connected to the vessel in an airtight manner remains on the vessel.The spring elements 14 are plugged at one end onto bolt-shaped receiving elements 15 and at the other end inserted into receiving elements 16, so that the spring elements 14 cannot buckle laterally when pressed together and are arranged in a fixed position relative to the sealing element 11 and the pressure element 13.In order that the pressure element 13 can be placed exactly at a specific location on the cover, guide elements 17 and 18 are provided. They permit linear guidance of the pressure element 13 relative to the sealing element 11. the guide element 17 is designed as a guide bolt and the guide element 18 as a guide bushing.The packaging container or the container and the lid can preferably be made of a plastic, in particular of the same plastic. In order to close the container with the lid in an airtight manner after filling with the food, the device 10 is placed on the packaging container. In the process, the pressure element 13 presses against the lid, whereby the lid is fixed to the vessel for the sealing process. The sealing surface 12 also presses against the lid above an opening edge of the vessel. During the sealing process, heat is supplied to the lid, the vessel and any joining agent therebetween through the sealing surface 12. As a result, the vessel and the lid can be connected to one another in a materially bonded and thus air-tight manner.After the sealing operation is complete, the device 10 is lifted from the packaging container. In this case, the sealing element 11 is separated from the lid, wherein the pressure element 13 presses against the lid and thus ensures that the lid remains on the vessel and the airtight sealing of the packaging container is ensured.LIST OF REFERENCE CHARACTERS10 Device 11 Sealing element 12 Sealing surface 13 Pressure element 14 Spring element 15 Receiving element 16 Receiving element 17 Guide element 18 Guide element

Claims

Device (10) for the thermal sealing of a packaging container with a container and a lid for a food product, with a sealing element (11) and a pressure element (13) for pressing the lid onto the container, characterized in that, when the sealing element (11) is lifted off the lid, the pressure element (13) can be pressed against the lid.Device (10) according to the preceding claim, characterized in that at least one spring element (14) is arranged between the sealing element (11) and the pressure element (13).Device (10) according to the preceding claim, characterized in that the at least one spring element (14) is fixed with receiving elements (15, 16) at one end to the sealing element (11) and at the other end to the pressure element (13).Device (10) according to one of the preceding claims, characterized in that the pressure element (13) can be guided relative to the sealing element (11) by means of guide elements (17, 18).Device (10) according to one of the preceding claims, characterized in that the sealing element (11) has a closed, encircling sealing surface.Device (10) according to one of the preceding claims, characterized in that the pressure element (13) is manufactured from a material which has a lower heat capacity than the material from which the sealing element (11) is manufactured.Device (10) according to one of the preceding claims, characterized in that the pressure element (13) is manufactured from a material which has a lower thermal conductivity than the material from which the sealing element (11) is manufactured.Device (10) according to one of Claims 3 to 6, characterized in that the receiving elements (15, 16) and / or the guide elements (17, 18) are likewise produced from a material which has a lower heat capacity than the material from which the sealing element (11) is produced.Device (10) according to one of Claims 3 to 6, characterized in that the receiving elements (15, 16) and / or the guide elements (17, 18) are likewise produced from a material which has a lower thermal conductivity than the material from which the sealing element (11) is produced.Device (10) according to claim 7, characterised in that the receiving elements (15, 16) and / or the guide elements (17, 18) and / or the pressure element (13) are manufactured from a plastic.Device (10) according to one of Claims 5 to 8, characterized in that the sealing surface (12) is provided with an anti-stick coating.Device (10) according to one of the preceding claims, characterized in that the sealing element (11) is made of metal.

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