Induction heating sealing device

Abstract

To provide an induction heating sealing device for providing a lateral sealing of a tube of a package material.SOLUTION: An induction heating sealing device for providing a lateral sealing of a tube of a package material includes: a body including first and second sealing surfaces arranged to face the package material in a sealing condition; and a conductor arrangement provided within the body for inducing an eddy current in the package material in the sealing condition. At least a part of the first and second sealing surfaces are inclined and include first and second upper parts, respectively, whereby particles within a product held inside the tube are forced away from a sealing zone of the tube as the sealing zone is pressed toward the first and second upper parts.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention generally relates to induction heat sealing. More particularly, the present invention relates to a device and method for providing a transverse seal of a tube of package material that holds a liquid food product.

Background Art

[0002] Today, it is well known to produce carton packages filled with liquid food products, such as Tetra Brik (trademark) packages filled with milk. The Tetra Brik (trademark) package machine is an example of a roll-fed package machine and is sometimes called a roll-fed filling machine. In a roll-fed package machine, a web of package material supplied to the package machine on a reel is formed into a tube and a longitudinal seal is provided. After the tube is formed and the longitudinal seal is provided, the tube is filled with product. A transverse seal is continuously created from the lower end of the tube. In connection with creating the transverse seal, the lower end of the tube is severed so that packages filled with the liquid product are formed. These packages are then transferred to a folding device, which folds the packages into their final form by using pre-created fold lines (sometimes called weakening lines) provided in the package material.

[0003] Another type of packaging machine is the so-called blank supply packaging machine. Unlike the roll supply packaging machine, packages are created one by one within the blank supply packaging machine. Another difference between the two is that the longitudinal seal is not created within the packaging machine but is pre-made. Thus, the blank should be regarded, in this context, as a sleeve-shaped piece of packaging material. Within the blank supply packaging machine, the blank is assembled, i.e., unfolded, so that an internal space is formed. After assembly, a closed end is formed by providing a transverse seal at one end of the sleeve. In the next step, the product is filled into the sleeve, and then the other end of the sleeve is closed by providing a transverse seal so that a closed package is formed.

[0004] To ensure that the product remains safely within the package, the transverse seal should be created by a reliable method. Techniques for providing a reliable transverse seal have been used for many years, but there is a continuing need to improve the transverse seal technology because requirements regarding speed, e.g., the number of packages produced per hour, different types of products filled into the package, e.g., highly viscous products and products containing seeds and other types of particles, maintenance intervals, etc., are continuously increasing.

Summary of the Invention

Problems to be Solved by the Invention

[0005] It is an object of the present invention to overcome at least partially one or more of the limitations defined above the prior art. Specifically, it is an object to provide an improved induction heating sealing device.

Means for Solving the Problems

[0006] According to a first aspect, an induction heating sealing device is provided for providing a transverse seal of a tube of packaging material, the induction heating sealing device comprising a body including first and second sealing surfaces arranged to face the packaging material in a sealing state, a recess provided in the body for receiving a knife during a cutting state, the first and second sealing surfaces being located on opposite sides of the recess, the recess, and a conductor arrangement provided in the body for inducing eddy currents in the packaging material in a sealing state, at least a portion of the first and second sealing surfaces being inclined and each having a first and a second upper part, whereby particles in a product held inside the tube are pushed away from a sealing zone of the tube when the first and second upper parts are pressed towards the sealing zone.

[0007] The induction heating sealing device may further include a magnetic flux concentrator arrangement for holding the conductor arrangement, the magnetic flux concentrator arrangement comprising one or several inclined magnetic flux concentrator upper surfaces forming part of the first and second sealing surfaces.

[0008] The conductor arrangement may comprise one or several inclined conductor arrangement upper surfaces forming part of the first and second sealing surfaces.

[0009] At least a portion of the first and second sealing surfaces may be inclined such that the direction in which the molten polymer in the packaging material is moved is controlled when the induction heating sealing device (300) is pressed towards the sealing zone.

[0010] The inclined profile of the first and second sealing surfaces of the heat sealing device (300) may be adapted to a specific type of packaging material having a specific type of polymer in the polymer layer.

[0011] Furthermore, the inclined profile of the first and second sealing surfaces of the heat sealing device may be adapted to a specific type of product containing a specific type of particles.

[0012] In addition, the inclined profiles of the first and second sealing surfaces of the heat-sealing device may be adapted to the dynamics of a particular type of filling machine.

[0013] According to a second aspect, there is provided a transverse sealing system including an induction heating sealing device according to the first aspect and a backpressure arrangement disposed on the opposite side of the induction heating sealing device, the induction heating sealing device and the backpressure arrangement being arranged such that, during operation, a tube can be fed between the two.

[0014] The backpressure arrangement may include first and second backpressure elements each having first and second pressure pad surfaces, the first and second backpressure pad surfaces being convex in shape.

[0015] The first pressure pad upper portion of the first convex pressure pad may be offset from the first upper portion of the first sealing surface of the induction heating sealing device, and the second pressure pad upper portion of the second convex pressure pad may be offset from the second upper portion of the first sealing surface of the induction heating sealing device.

[0016] According to a third aspect, there is provided a method for transversely sealing a tube of packaging material by using an induction heating sealing device including a body having first and second sealing surfaces arranged to face the packaging material in a sealed state, and a recess provided in the body for receiving a knife in a cut state, the first and second sealing surfaces being located on opposite side surfaces of the recess, and a conductor arrangement provided in the body for inducing eddy currents in the packaging material in a sealed state, at least a portion of the first and second sealing surfaces being inclined and each having first and second upper portions, and a backpressure arrangement disposed on the opposite side of the induction heating sealing device, the method comprising: placing the tube such that the sealing zone of the tube faces the induction heating sealing device and the backpressure arrangement; moving the induction heating sealing device and the backpressure arrangement towards each other such that particles of the product held inside the tube are pushed away; inducing eddy currents in the packaging material of the tube by using the induction heating sealing device; Pressing the first and second sides of the tube towards each other such that the molten polymer within the polymer layers on the first and second sides of the tube adheres to each other; Distributing the molten polymer using the inclined sealing surface of an induction heating sealing device so as to reduce the risk of an inadequate seal; and

[0017] Here, embodiments of the present invention are described by way of example with reference to the accompanying schematic diagrams.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0019] FIG. 1 generally shows a packaging machine 100. In the example shown, the packaging machine 100 is a roll-fed carton packaging machine. The general principle of such a machine is that a web 102 is formed from a roll of packaging material. Although not shown, the web 102 may be sterilized using a hydrogen peroxide bath, a low voltage electron beam (LVEB) device or any other device capable of reducing a number of undesirable microorganisms, if necessary to meet food safety regulations. After sterilization, the web 102 may be formed into a tube 104 by using a longitudinal sealing device. Once the tube is formed, a product, such as milk, may be fed into the tube 104 via a product pipe 106 placed at least partially inside the tube 104.

[0020] To form the package 108 from the tube 104 filled with product, a transverse seal may be created at the lower end of the tube by using a sealing device 110. Generally, the sealing device 110 has two main functions, namely providing a transverse seal, i.e., welding together two opposing sides of the tube such that the product in the lower part of the tube placed below the sealing device is separated from the product in the tube placed above the sealing device, and severing the lower part of the tube such that the package 108 is formed. Alternatively, instead of providing a transverse seal and severing the lower part with the same device as shown, the step of severing the lower part may be performed in a subsequent step by a different device or by the consumer if the package is intended to be sold within a multipack.

[0021] In FIG. 2, the general principles of the sealing device 110 are shown in more detail. The tube 104 can be fed from above, which enables the product to be held inside the tube. In the first stage, the sealing stage S, a first jaw with a sealing device 200 and a second jaw with a counterpressure device 202 are moved towards each other such that two opposing sides of the tube 104 are pressed towards each other. To provide a transverse seal, heat can be provided by inducing eddy currents in the package material while pressing the two opposing sides together. The heat melts the polymer layer of the package material, thereby providing a polymer layer that can then be used to ensure that the two opposing sides adhere to each other and stay together after the jaws are removed. In a subsequent step (referred to herein as the cutting stage C), the lower part of the tube 104 can be severed such that the package 108 is formed. To increase the speed at which the package is formed, the jaws may be moved with the tube 104 in the tube feed direction A during the sealing stage S and the cutting stage C.

[0022] To provide a more controlled forming process for the package 108, so-called volume forming flaps 204a, 204b can be used. More specifically, by using these, a tube 104 having a circular cross-section may be advanced in a controlled manner into a package 108 having a rectangular cross-section.

[0023] The sealing device can comprise two inductors, a first inductor 206a and a second inductor 206b. In the example shown, the first inductor 206a is disposed on top of the second inductor 206b. After providing a transverse seal, the knife 208 is used to sever the lower portion of the tube, and thus the package 108 can be formed. In this example, the knife 208 as well as the first and second inductors 206a, 206b are provided within the sealing device, although other arrangements are possible. For example, the knife may be provided on the opposite side of the tube within a backpressure device, or the cutting step may be performed by a separation device downstream of the sealing device.

[0024] In FIG. 3, an induction heating sealing device 300 which may form part of the sealing device 110 is shown in detail as an example. More specifically, the induction heating sealing device 300 may be used as the sealing device 200 shown in FIG. 2.

[0025] The induction heating sealing device 300 may include a body 302. Within the body 302, magnetic flux concentrator arrangements 304a - d may be provided. The purpose of the magnetic flux concentrator arrangements 304a - d is to enable the electromagnetic radiation formed by the electrical conductor arrangements 306a - d (which may also be included within the body 302) to be directed towards the tube 102 of the packaging material during the sealing stage S. The magnetic flux concentrator arrangements 304a - d can be made from various materials such as plastiferrites or soft magnetic composite materials.

[0026] The induction heating sealing device 300 may be designed in various ways. In FIG. 3, a so-called twin coil inductor is shown as an example. In the twin coil inductor, the electrical conductor arrangements 306a - d may include a first coil 306a - b and a second coil 306c - d, that is, one coil is provided on either side of the recess 308 configured to receive a knife during the cutting stage C. Another option is a so-called single coil inductor, in which case one coil is provided and arranged such that a part of the coil is provided on one side of the recess 308 and another part of the coil is provided on the other side of the recess 308. In short, the first inductor 310 and the second inductor 312, representing the first part of the body 302 on one side of the recess 308 and the second part of the body 302 on the other side of the recess 308 respectively, may share a single coil or may each have one coil as shown in FIG. 3.

[0027] Furthermore, as shown, the electrical conductor arrangements 306a - d may be held by the magnetic flux concentrator arrangements 304a - d such that the electrical conductor arrangements 306a - d form part of the outer surface of the body 302. Another option, not shown, is that the electrical conductor arrangements 306a - d are completely held within the magnetic flux concentrator arrangements 304a - d such that the electrical conductor arrangements 306a - d do not form part of the outer surface of the body 302. A further option is to have a surface cover (not shown) such that neither the magnetic flux concentrator arrangements 304a - d nor the electrical conductor arrangements 306a - d form part of the outer surface.

[0028] The first and second sealing surfaces 314a, 314b of the first and second inductors 310, 312, respectively, may be inclined as shown in FIG. 3. There are several advantages to having inclined first and second sealing surfaces 314a, 314b. First, during the sealing stage S, particles within the food product within the tube 104 may be extruded in a more controlled manner from the sealing zone of the tube 104, i.e., the section of the tube 104 formed by the transverse seal, as compared to having an inductor with a flat surface. More specifically, the effect of having inclined first and second sealing surfaces 314a, 314b is that a pressure gradient can be constructed within the tube 104 without problems. Various products differ, for example, with respect to viscosity and whether the product contains particles, and if the product contains particles, these can have various characteristics, so various products may require various criteria to avoid product residue within the sealing zone. By customizing the inclined profile based on the product held within the tube 104, i.e., how the sealing surfaces 314a, 314b are inclined, the construction of the pressure gradient can be optimized for the product, suggesting an even further improved transverse seal.

[0029] In addition to the improvement in which product residue is appropriately removed from the sealing zone during the sealing stage S, having inclined sealing surfaces 314a, 314b also has a beneficial effect on the quality of the seal. The pressure gradient is also formed within the polymer layer that melts during the sealing stage S. Thereby, the way in which the molten polymer within the packaging material is moved can be controlled in a more accurate manner as compared to using an inductor with a flat surface. This can then reduce the risk of the molten polymer aggregating within the packaging material. In short, the molten polymer can be distributed more efficiently. Another beneficial effect is that less polymer may be required to create a reliable transverse seal. Since the way in which the molten polymer is distributed during the sealing stage S may be controlled in a more accurate manner, this may suggest that less polymer is required, which is advantageous not only from a cost perspective but also from an environmental perspective.

[0030] In the example shown in FIG. 3, the first and second sealing surfaces 314a, 314b each include first and second upper portions 316a, 316b. As shown, in this example, the first and second upper portions 316a, 316b are positioned adjacent to the recess 308, although other arrangements of the first and second upper portions 316a, 316b are possible. Further, as shown in FIG. 3, the upper surfaces 318a - d of the flux concentrator can be inclined to form part of the first and second sealing surfaces 314a, 314b. As shown, the upper surfaces 320a - d of the electronic conductor arrangement may also be inclined to form part of the sealing surfaces 314a, 314b. Further, the first and second sealing surfaces 314a, 314b may be symmetric with respect to the recess axis RA passing through the recess 308.

[0031] FIG. 4 generally shows a transverse sealing system 400 including an induction heating sealing device 300, and then a backpressure arrangement 402a, 402b including first and second backpressure elements 402a, 402b.

[0032] The induction heating sealing device 300 shown in FIG. 4 differs from the induction heating sealing device shown in FIG. 3 in that the first and second upper portions 316a, 316b are positioned at the respective central portions of the first and second sealing surfaces 314a, 314b, rather than adjacent to the recess 308 as in the example shown in FIG. 3. Further, only a part of the sealing surfaces 314a, 314b in the example shown in FIG. 4 is inclined, that is, the sealing surfaces 314a, 314b include inclined portions and flat portions.

[0033] The first and second backpressure elements 402a, 402b may each include first and second backpressure pads 404a, 404b, which may be made of, for example, rubber or other elastic materials. The first and second backpressure pads 404a, 404b can include first and second backpressure pad surfaces 406a, 406b arranged to face the tube 104 during the sealing stage S. The first and second backpressure pad surfaces 406a, 406b are convex in shape and can each include first and second backpressure pad upper portions 408a, 408b.

[0034] As shown in FIG. 4, the first and second upper reverse pressure pads 408a, 408b are offset with respect to the first and second upper parts 316a, 316b, and herein, the first pressure pad upper FPPTS axis passing through the first upper reverse pressure pad 408a, the second pressure pad upper SPPTS axis passing through the second upper reverse pressure pad 408b, the first upper FTS axis passing through the first upper part 316a, and the second upper STS axis passing through the second upper part 316b are shown. Although not shown, it is also possible to have the first and second upper reverse pressure pads 408a, 408b aligned with respect to the first and second upper parts 316a, 316b.

[0035] Furthermore, as represented above, the inclined profiles of the first and second sealing surfaces 314a, 314b may be adjusted to meet the requirements of a particular product, a particular packaging material, a particular type of sealing device 110, a particular packaging machine 100, or a combination thereof. In addition, in order to further improve the sealing characteristics, the inclined profiles of the first and second reverse pressure pad surfaces 406a, 406b may also be adjusted to meet the above requirements.

[0036] In addition, the first and second reverse pressure elements 402a, 402b may be of different shapes such that the first and second reverse pressure pad surfaces 406a, 406b have different inclined profiles. One reason for these having different shapes is that the tube 104 placed upstream of the transverse sealing system 400 provides the pressure exerted by the food product held within the tube 104 onto the transverse sealing system 400. By having the first and second reverse pressure elements 402a, 402b and optionally also or instead the first and second inductors 310, 312 of different shapes, the pressure exerted by the food product can be compensated for.

[0037] FIG. 5 is a flowchart 500 showing a method for laterally sealing a tube 104 of package material by using an induction heating sealing device 300. The method includes placing the tube 104 such that the sealing zone of the tube faces the induction heating sealing device 300 and the backpressure arrangements 402a, 402b (502); moving the induction heating sealing device 300 and the backpressure arrangements 402a, 402b towards each other such that particles of the product held inside the tube are pushed away (504); inducing eddy currents in the package material of the tube by using the induction heating sealing device 300 (506); pressing the first and second sides of the tube 104 towards each other such that the molten polymer in the polymer layers on the first and second sides of the tube adheres to each other (508); and distributing the molten polymer by using the inclined sealing surface of the induction heating sealing device 300 such that the risk of an insufficient seal is reduced (510).

[0038] As described and shown above, various embodiments of the invention have been described and shown, but the invention is not limited thereto and may be embodied in other ways within the scope of the subject matter defined in the following claims.

Claims

Claim 1 An induction heating sealing device (300) for providing a transverse seal of a tube (104) of package material, comprising: A body (302) including first and second sealing surfaces (314a, 314b) arranged to face the package material in a sealed state (S); A recess (308) provided in the body (308) for receiving a knife during a cutting state (C), wherein the first and second sealing surfaces (314a, 314b) are placed on opposite side surfaces of the recess (308); A conductor arrangement (306a, 306b, 306c, 306d) provided in the body (302) for inducing eddy currents in the package material during the sealed state (S); And comprising At least a part of the first and second sealing surfaces (314a, 314b) is inclined and has first and second upper parts (316a, 316b) respectively, whereby particles in the product held inside the tube (104) are pushed away from the sealing zone of the tube when the first and second upper parts (316a, 316b) are pressed towards the sealing zone. Induction heating sealing device (300). Claim 2 The induction heating sealing device (300) according to claim 1, further comprising a magnetic flux concentrator arrangement (304a, 304b, 304c, 304d) for holding the conductor arrangement (306a, 306b, 306c, 306d), and the magnetic flux concentrator arrangement (304a, 304b, 304c, 304d) comprises one or several inclined magnetic flux concentrator upper surfaces (318a, 318b, 318c, 318d) forming a part of the first and second sealing surfaces (314a, 314b). Claim 3 The induction heating sealing device (300) according to claim 1 or 2, wherein the conductor arrangement (306a, 306b, 306c, 306d) comprises one or several inclined conductor arrangement upper surfaces (320a, 320b, 320c, 320d) forming a part of the first and second sealing surfaces (314a, 314b). Claim 4 The induction heating sealing device (300) according to any one of claims 1 to 3, wherein at least a part of the first and second sealing surfaces (314a, 314b) is inclined such that when the induction heating sealing device (300) is pressed towards the sealing zone, the direction of movement of the molten polymer in the package material is controlled. Claim 5 The induction heating and sealing device (300) according to any one of claims 1 to 4, wherein the inclined profiles of the first and second sealing surfaces (314a, 314b) of the heating and sealing device (300) are adapted to a specific type of packaging material having a specific type of polymer in the polymer layer.

6. The induction heating and sealing device (300) according to any one of claims 1 to 5, wherein the inclined profiles of the first and second sealing surfaces (314a, 314b) of the heating and sealing device (300) are adapted to a specific type of product containing a specific type of particle.

7. The induction heating and sealing device (300) according to any one of claims 1 to 6, wherein the inclined profiles of the first and second sealing surfaces (314a, 314b) of the heating and sealing device (300) are adapted to the dynamics of a specific type of filling machine.

8. A transverse sealing system (400), comprising the induction heating and sealing device (300) according to any one of claims 1 to 7, and a backpressure arrangement (402a, 402b) disposed on the opposite side of the heating and sealing device (300), wherein the induction heating and sealing device (300) and the backpressure arrangement (402a, 402b) are arranged such that, during operation, the tube (104) can be fed between the two, the transverse sealing system (400).

9. The transverse sealing system (400) according to claim 8, wherein the backpressure arrangement (402a, 402b) includes first and second backpressure elements (402a, 402b) each having first and second pressure pad surfaces (406a, 406b), and the first and second backpressure pad surfaces (406a, 406b) are convex in shape.

10. The first pressure pad upper portion (408a) of the first convex pressure pad (404a) is offset from the first upper portion (316a) of the first sealing surface (314a) of the induction heating and sealing device (300), and the second pressure pad upper portion (408b) of the second convex pressure pad (404b) is offset from the second upper portion (316b) of the first sealing surface (314b) of the induction heating and sealing device (300), the transverse sealing system (400) according to claim 9.

11. A body (302) including first and second sealing surfaces (314a, 314b) arranged to face a packaging material in a sealed state (S), and a recess (308) provided in the body (308) for receiving a knife during a cutting state (C), wherein the first and second sealing surfaces (314a, 314b) are placed on opposite side surfaces of the recess (308), a recess (308), and a conductor arrangement (306a, 306b, 306c, 306d) provided in the body (302) for inducing eddy currents in the packaging material in the sealed state (S), an induction heating sealing device (300), at least a part of the first and second sealing surfaces (314a, 314b) being inclined and each having first and second upper portions (316a, 316b), an induction heating sealing device (300), and a method (500) for transversely sealing a tube (104) of the packaging material by using a backpressure arrangement (402a, 402b) arranged on the opposite side of the induction heating sealing device (300), placing the tube (104) such that a sealing zone of the tube faces the induction heating sealing device (300) and the backpressure arrangement (402a, 402b) (502); moving the induction heating sealing device (300) and the backpressure arrangement (402a, 402b) towards each other so that particles of the product held inside the tube are pushed away (504); inducing eddy currents in the packaging material of the tube by using the induction heating sealing device (300) (506); pressing the first and second side surfaces of the tube (104) towards each other such that the molten polymer in the polymer layers of the first and second side surfaces of the tube adheres to each other (508); distributing the molten polymer by using the inclined sealing surface of the induction heating sealing device (300) so as to reduce the risk of insufficient sealing (510) and a method (500) including the above.

Images