SIEGELORGAN

Description

[0001] The invention relates to improvements in sealing organs.

[0002] The term "sealing" refers herein to the material-to-material joining, in particular of plastics, primarily for the production of packaging made of thermoplastic materials such as plastic films or film composites, such as plastic films coated with metallic and non-metallic materials, metal films coated with thermoplastic plastic such as aluminium foil and the like, for example in the production of tubular bags, the closing of containers, for example by sealing plastic film with or without aluminium coating, plastic-coated aluminium foil or other thermally weldable materials onto containers made of plastic with or without coating or made of aluminium with a plastic coating, or the sealing / welding of films or film composites of the type mentioned above.

[0003] Heated sealing tools (also known as sealing elements) are typically used for sealing. These typically consist of a heating cartridge (a wound resistance conductor) and a base body in which the heating cartridge and a temperature sensor required for temperature control are integrated.

[0004] WO 2018 / 055034 A1 describes a sealing element in which heat-generating elements of a heating element are contacted from the rear side of the heating element. Further aspects relate to a sealing element in which the location of heat generation and the location of heat dissipation (i.e., the effective point) are arranged as close to each other as possible, a heating element with an integrated temperature sensor, and a sealing element with the option of cooling or sucking in the heating element and / or the material to be welded as needed.

[0005] Common sealing elements, such as sealing jaws, typically have a flat contact surface. Exceptions are so-called sealing wheels, whose circular outer contour is heated. However, this outer contour does not correspond to the shape of the material to be sealed; rather, it serves to continuously roll the round sealing wheel on an essentially flat material, thus continuously creating a sealed seam, for example, in the production of tubular bags as they are pulled off a forming shoulder.

[0006] However, there are various applications where a three-dimensionally shaped structure must be sealed. One example is so-called "spout bags," i.e., bags of various types equipped with a screw-on resealable closure. The "spout" is a plastic injection-molded part that provides a threaded spout that can be opened and closed with a screw cap. Spouts are typically used either in an upper corner (e.g., personal care products, cleaning agents) or in the center of the upper edge of the bag (e.g., beverages, fruit puree), depending on the application or product.

[0007] The maximum thickness of the spout is determined by the outer diameter of the spout. To allow the spout to be sealed between two film layers, the plastic injection-molded part has a thickness that decreases toward both sides, starting with the greatest thickness in the center of the spout. This allows the two films to be sealed directly together beyond the spout without cracking. The contour to be sealed is thus three-dimensional because the surfaces of the spout to be sealed are curved, i.e., simply bent.

[0008] WO 2006 / 042692 A2 discloses a plastic bag made of plastic film with one or more ports, as well as a sealing element for its production. At least one of these ports comprises a plastic element that is welded between two layers of plastic film, thereby forming a port welding area β. In the port welding area (50), the plastic element (40) can be compressed flat. The cross-section of the unloaded, non-compressed, plastic element (40) is wedge-shaped in the direction toward the lateral edges of the port welding area (50). The plastic element (40) comprises at least one first edge (80) in the port welding area (50). The plastic bag (10) enables an optimized production process and is particularly suitable for use in the medical field.

[0009] DE 10 2016 117834 A1 discloses, among other things, a sealing element in which heat-generating elements of a heating element are contacted from its rear side.

[0010] The core of the present invention is the segmented, mosaic-like arrangement and electrical connection of heating elements for heating 3-dimensional surfaces, whereby the heating can be carried out contact-based or contactless (by means of radiant heat / convection heat).

[0011] The invention provides a sealing member which is capable of producing both flat and three-dimensional sealing seams discontinuously, i.e., for example, sealing a workpiece with single-curved (i.e., bent) or double-curved (i.e., arched) outer contours, for example, welding a film or welding the workpiece between two films.

[0012] In one embodiment, the proposed sealing member for thermally bonding thermoplastic materials along a curved or arched contour comprises a plurality of heating elements, as well as at least one contour element which has a curved or arched contour, wherein the heating elements are arranged on the contour element and wherein, according to the invention, the heating elements each comprise a flat carrier substrate with a front side and a back side, on the front side of which at least one heating circuit is arranged.

[0013] The term "flat" in this context means, for example, "in the shape of a plate," where the plate can be flat, curved, or arched. The particular advantage of the invention comes into play when easily manufactured, flat, relatively small heating elements are combined in such a way that, through the interaction of a plurality of such heating elements, a complex, curved, or arched sealing contour is created.

[0014] In the simplest case, a carrier substrate contains precisely one heating circuit, which is produced, for example, from metal using a thin-film coating process or from conductive paste or conductive ceramic slip using a thick-film printing process. However, the inventive concept also encompasses embodiments in which two or more heating circuits are arranged on a carrier substrate. Advantageously, it can be provided that the heating elements can be controlled individually. Particularly advantageously, it can be provided that each individual heating circuit can be controlled separately from all other heating circuits, even those located on the same carrier substrate, with regard to its heating output or target temperature.

[0015] According to one embodiment, the sealing element has a control or regulating device or can be connected to a control or regulating device that enables the separate control or regulation of all heating circuits. Such a control or regulating device can be arranged either alone or together with power electronics in a housing of the sealing element. Alternatively, the power electronics can also be part of a packaging machine, for which the sealing element is used as a component, if the sealing element is connected to the power electronics of the packaging machine.

[0016] According to another embodiment, the heating circuits of the heating elements are contacted from the rear side of the carrier substrates through the respective carrier substrate. Alternatively or additionally, it can be provided that the control or regulating device is connected to the heating circuits of the heating elements by a flexible printed circuit board, through which the heating circuits of the heating elements are electrically contacted. The combination of these two embodiments results in an embodiment in which a flexible printed circuit board has conductor tracks that lead from a control or regulating device and / or power electronics to all heating elements and contact their heating circuits from the rear side of the respective carrier substrates. For this purpose, the carrier substrates can have, for example, VIAs (Vertical Interconnect Access), i.e. conductive through-holes.In addition, the flexible printed circuit board can have so-called landing pads (contact islands) in the area of ​​the VIAs, which can be connected to contact points arranged on the back of the carrier substrates, for example by soldering, bonding, gluing with conductive adhesive, ultrasonic welding or other suitable contacting methods.

[0017] The flexible circuit board also simplifies the universal use of an arrangement of heating elements produced in this way, as the heating elements, which are flexibly connected to one another by the circuit board, can be attached, if necessary, to another contour element whose front side has a different contour to be sealed. According to a further embodiment, the heating elements or, if provided, the second front-side contour element, are covered by a cover element whose front side has the contour to be sealed. The cover element can, for example, be made of an electrically non-conductive material to prevent short circuits and, at the same time, provide the sealing element with an abrasion-resistant layer. If the heating elements are attached with their front side to the back of a second contour element, the second contour element can alternatively also simultaneously assume the function of the cover element.

[0018] The proposed sealing element can, for example, comprise several small (e.g., between 2 mm x 2 mm and 20 mm x 20 mm), flat, rectangular, square, or otherwise shaped heating elements, each of which has at least one heating circuit and, advantageously, an integrated temperature measurement capability. The heating elements can, for example, consist of printed ceramic, metallic, or plastic-based carrier substrates.

[0019] The heating elements can be arranged, for example, in a mosaic-like manner, corresponding to a three-dimensional structure to be heated. Differently sized elements can be combined in the mosaic to achieve the most precise (step-like) representation of the three-dimensional contour.

[0020] In the case of contact heating, the heating elements can additionally be thermally coupled to a metallic heat exchanger (e.g. a sealing profile sheet), which represents a negative of the three-dimensional surface to be heated.

[0021] Electrical contact can be achieved, for example, using a flexible foil cable (e.g., made of polyimide) in a "pearl necklace." The electrical connection between the flexible foil cable and the heating elements can be achieved, for example, by soldering, sintering, or welding. The flexible foil cable used can also contain a rigid component (so-called rigid-flex).

[0022] For this purpose, heating elements are electrically contacted in a flat arrangement and then arranged along the correspondingly shaped back of the sealing profile sheet (corresponding to the contour to be sealed) and thermally contacted. The electrical contact of the heating elements is preferably made on the back of the heating elements, which ensures the best possible homogeneity of the surface temperature on the active side.

[0023] For fixation, a first contour element can be attached to the back as a support structure, either by means of a material bond, for example, by welding, soldering, or sintering, or by force-fitting, for example, by pressing or clamping. This element also transmits the force and encapsulates the heating elements. The heating elements are thus not exposed to the force flow.

[0024] The second contour element located between the heating element and the three-dimensional surface to be heated, for example a profiled sheet, can have a maximum thickness of 1.5 mm (maximum distance between heating elements and profile surface) and can be subsequently machined (for example by milling, turning, grinding or the like) to precisely reproduce the three-dimensional surface.

[0025] The material used for the second contour element (e.g. metallic) has a high thermal conductivity coefficient (>100W / m*K).

[0026] In the case of contactless (radiant) heating, the second contour element on the front side can be omitted and the heating elements can, for example, be materially integrated into high-temperature-resistant insulation materials on the back.

[0027] The electrical contact between the heating elements can be achieved, for example, by means of welded wires, welded, soldered, or sintered contact pins, or similar methods. The electrical contact can be made on both the front (active side) and the back of the heating elements.

[0028] The overall assembly may further include an insulating body made of thermally insulating material between the heating element and the housing. The housing may be made of metallic or thermally insulating material.

[0029] The sealing elements, characterized by a large number (at least two) of individual heating elements, are equipped with a corresponding multi-channel control or regulation device and temperature measurement. These are preferably integrated into the housing of the assembly. If installation space and operating conditions do not permit this, this control or regulation device can also be placed in a separate housing at an appropriate distance from the heating elements.

[0030] The heating elements can advantageously have the function of both resistive heating and resistive temperature measurement. For this purpose, the (individual) heating circuit arranged on the carrier substrate of a heating element can be used directly for temperature measurement by having a sufficient temperature-dependent heating resistance. Alternatively or additionally, a separate measuring conductor can be arranged on the carrier substrate of the heating element, which has a high (>1000 ppm / K) temperature-dependent resistance.

[0031] In the following, examples of the proposed sealing device are explained in more detail using drawings. Fig. 1 a first embodiment of the sealing element without cooling device, Fig. 2 the heater assembly Fig. 1 , Fig. 3 an exploded view of the heater assembly from Fig. 2 , Fig. 4 the arrangement of the heating elements in the heater assembly of the Fig. 2 and 3 , Fig. 5 a second embodiment of the sealing element with cooling device, Fig. 6 the arrangement of the heating elements in the heater assembly of the Fig. 5 .

[0032] Fig. 1 to 4 relate to a first embodiment of the proposed sealing element, in which an insulating body 5, which simultaneously acts as a support element for a heater module, is attached to a housing 6 with a plug connector 61.

[0033] The heater module comprises a first contour element 3, which simultaneously acts as a support structure for the heating elements, and a second contour element 4, which simultaneously serves as a cover structure for the heating elements. The first contour element 3 can be made of the same material as the second contour element 4 and can be integrally connected to it (e.g., welded or soldered).

[0034] Between the first contour element 3 and the second contour element 4, an arrangement of heating elements is enclosed and encapsulated, each having a carrier substrate 1, wherein the carrier substrates 1 each have at least one heating circuit on their front side.

[0035] The two end regions of the heating element array consist of carrier substrates 1A, each with exactly one heating circuit. The central region, which has a curved contour, consists of carrier substrates 1B, each with multiple heating circuits.

[0036] On their rear sides, the carrier substrates 1 have contact islands 11 through which the heating circuits arranged on the front side of the carrier substrate are electrically contacted. For this purpose, corresponding conductor structures of a flexible printed circuit board 2 are connected to the contact islands 11. The heating circuits are electrically contacted by means of vias from the rear side of the carrier substrates 1 through the latter.

[0037] For this purpose, the carrier substrates 1 of the heating elements have through-contacts, so-called vias, which are connected to the heating elements on the front side of the carrier substrates 1. A flexible circuit board 2 with conductor tracks for contacting each individual heating element extends across the back of the entire arrangement of carrier substrates 1, and the conductor tracks arranged thereon are electrically connected to the vias. The flexible circuit board 2 mechanically connects all carrier substrates 1 to one another. The flexibility of the circuit board 2 ensures that the entire arrangement of carrier substrates 1 is flexible and can therefore be adapted to a three-dimensional contour.

[0038] The rear first contour element 3 is connected by means of a support element 5 to a housing 6, in which, for example, a control or regulating device can be arranged. This control or regulating device can, for example, continuously switch back and forth between a heating mode, in which the heating element is supplied with heat energy, and a temperature measurement mode, in which the temperature-dependent, variable resistance of the heating element is determined. This makes it possible to regulate the heat energy supplied to each heating circuit so that either all heating circuits reach the same temperature (homogeneous temperature distribution) or different heating circuits reach different temperatures (heterogeneous temperature distribution).

[0039] Fig. 5 and 6relate to a second embodiment of the proposed sealing element, which is fundamentally constructed in the same way as the first embodiment, so that reference can be made to the above description in this respect. However, the following differences exist: The heating elements used in this embodiment are all of the type in which exactly one heating circuit is arranged on a carrier substrate 1A. In contrast to the first embodiment, there are no heating elements here in which a carrier substrate carries multiple heating circuits. As in the first embodiment, the heating elements are contacted by a flexible printed circuit board 2, which is connected to contact islands 11 on the back of the carrier substrates 1.

[0040] In this exemplary embodiment, the sealing element further comprises a cooling device comprising a heat dissipating body 7, which is connected to an actively operated fluidic cooling unit. For example, it can be provided that the rear first contour element 3 is simultaneously designed as a heat dissipating body 7. For this purpose, the first contour element 3 can, for example, have coolant channels. Alternatively, as for this exemplary embodiment in Fig. 5shown, a separate heat dissipating body 7 (for example a shaped sheet metal or correspondingly milled component) can be arranged on the back of the first contour element 3. The heat dissipating body can be attached to the first contour element 3 in such a way that the heat flow between the spout area, which is generally operated at a higher temperature, and the two flat end areas of the seal, in which only the films are sealed to one another on both sides of the spout, is reduced. In the exemplary embodiment, the heat dissipating body 7 has an angle profile, one leg of which is only formed in the two end areas of the heater module, where the two tabs formed by this leg of the angle profile engage behind the first contour element and absorb its heat there. In the exemplary embodiment of the Fig. 5The cooling device further comprises a heat sink 8, which is in thermally conductive connection with the second, continuous leg of the heat dissipation body 7 and which has coolant connections through which the heat sink 8 is supplied with coolant from a cooling unit (not shown), which dissipates the heat transferred from the heat dissipation body 7 to the heat sink 8. This enables a sharp temperature demarcation within the contour element and thus the sealing surface of up to over 50K. List of reference symbols

[0041] 1Carrier substrate 1ACarrier substrate with one heating circuit 1BCarrier substrate with multiple heating circuits 11Contact island 2Flexible printed circuit board 3First contour element, carrier structure 4Second contour element, cover structure 5Insulating body, support element 6Housing 61Connector 7Heat dissipator 8Heat sink

Claims

1. A sealing element for thermally connecting thermoplastic materials along an arcuate or arched contour, comprising a plurality of heating elements and at least one contour element (3, 4) which has an arcuate or arched contour, the heating elements being arranged on the contour element (3, 4), characterized in that the heating elements each comprise a flat carrier substrate (1) with a front side and a rear side, on the front side of which at least one heating circuit is arranged.

2. The sealing element as claimed in claim 1, in which the heating elements are produced in a thick film printing method from conductive paste or conductively prepared ceramic slurry.

3. The sealing element as claimed in either of claims 1 and 2, in which the heating elements are produced in a thin film coating method from metal.

4. The sealing element as claimed in one of claims 1 to 3, which comprises an open-loop or closed-loop control device or can be connected to an open-loop or closed-loop control device, wherein each heating element can be actuated with regard to its heating performance or the target temperature separately from all the other heating elements.

5. The sealing element as claimed in one of claims 1 to 4, in which the heating elements are contacted electrically by means of a flexible printed circuit board (2).

6. The sealing element as claimed in claim 5, in which the electric contacting takes place by way of sintering, soldering, bonding, adhesive bonding using a conductive adhesive, or ultrasonic welding.

7. The sealing element as claimed in one of claims 1 to 6, in which the heating circuits are contacted electrically from the rear side of the carrier substrates (1) through the respective carrier substrate (1).

8. The sealing element as claimed in one of claims 1 to 7, in which the carrier substrates (1) with the heating circuits attached on them are encapsulated between a rear-side first contour element (3), which acts as a carrier structure, and a front-side second contour element (4), which acts as a cover structure.

9. The sealing element as claimed in one of claims 1 to 8, further comprising a cooling device with a heat dissipation body which is connected to a cooling unit.

10. The sealing element as claimed in claim 9, in which the first contour element (3) is at the same time configured as a heat dissipation body.

11. The sealing element as claimed in claim 9, in which a separate heat dissipation body is arranged on the first contour element (3).