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EP-4590494-B1 - PACKAGING MACHINE WITH SEALING DEVICE FOR PAPER WRAPPING MATERIALS

EP4590494B1EP 4590494 B1EP4590494 B1EP 4590494B1EP-4590494-B1

Inventors

  • FRASNETTI, LUCA
  • BOLOGNESI, DANIELE
  • SORRENTINO, STEFANO

Dates

Publication Date
20260513
Application Date
20230918

Claims (15)

  1. Packaging machine (1) for packaging tissue paper products, such as kitchen towel rolls and toilet rolls, by wrapping a paper wrapping sheet around the products, the machine comprising: ∘ a product feeding station (2) for grouping and feeding, one by one in succession, groups of products comprised of at least one product, ∘ a wrapping station (19) for wrapping the paper wrapping sheets around the groups of products, ∘ downstream of the wrapping station, a sealing station (40) for sealing the paper wrapping sheets wrapped around the groups of products, wherein the sealing station (40) comprises a channel (41) for moving forward the groups of products and a pair of sealing members (42A, 42B) provided opposite each other on two sides of said channel, each sealing member having a uniform sealing surface (43A, 43B) made of a material of the type in which eddy currents can be induced when the material is subjected to a change in the magnetic field, each sealing member comprising at least one flexible element (70) driven between at least two return members (44A, 45A, 46A; 44B, 45B, 46B), the sealing members being respectively associated with an electromagnetic induction device (48A, 48B) adapted to induce eddy currents in said material, wherein both sealing members are formed by at least one uniform tape (54A, 54B) of the material in which eddy currents can be induced, defining the uniform sealing surface (43A, 43B).
  2. The packaging machine of one or more of the previous claims, wherein each electromagnetic induction device (48A, 48B) comprises an induction coil (49A, 49B) arranged facing frontally the sealing surface (43A, 43B) or arranged at the opposite side of the sealing member (42A, 42B) with respect to the sealing surface.
  3. The packaging machine of one or more of the previous claims, wherein the electromagnetic induction device (48A, 48B) is configured to heat the sealing surface (43A, 43B) up to a temperature comprised between 100° C and 400° C.
  4. The packaging machine of one or more of the previous claims, comprising an adjustment device for adjusting the mutual distance of the sealing members (42A, 42B).
  5. The packaging machine of one or more of the previous claims, comprising adjustment members (76) for adjusting the sealing pressure.
  6. The packaging machine of one or more of the previous claims, wherein the induction device (48A, 48B) associated with each sealing element is external and is supplied with an induction current having a frequency comprised between 1 kHz and 500 kHz.
  7. The packaging machine of one or more of the previous claims, wherein at least one of the return members (44A, 45A, 46A; 44B, 45B, 46B) is motorized (M1, M2).
  8. The packaging machine of one or more of the previous claims, wherein said channel (41) comprises a conveyor (47) for moving forward the groups of products along the sealing station (40) according to a moving forward direction, the forward movement of the groups of products being preferably caused by the conveyor (47) and the sealing members (42A, 42B).
  9. The packaging machine of one or more of the previous claims, wherein the wrapping station (19) provides for an exit speed of the groups of products and wherein the conveyor (47) and the sealing members (42A, 42B) are configured to move forward the groups of products at a speed higher than the speed at which the products exit the wrapping station (19).
  10. The packaging machine of one or more of the previous claims, wherein the paper wrapping sheet comprises a sealant (S).
  11. The packaging machine of claim 10, wherein the sealant (S) is a heat activated adhesive.
  12. The packaging machine of one or more of the previous claims, wherein the feeding station (2) comprises an elevator (16) for lifting a group of products toward the wrapping station (19), the groups of products touching the wrapping sheet (F) that is arranged parallel to a plane transverse with respect to the direction of lifting (f16) of the group of products, the wrapping sheet (F) forming, around the group of products, a partial wrapping shaped like an overturned U.
  13. The packaging machine of one or more of the previous claims, wherein the wrapping station (19) comprises: ∘ a bottom folding device (25, 26) for completing the partial wrapping of the wrapping sheet (F) around the group of products, forming a tube open at two opposite sides of the group of products, the open tube having flaps of wrapping sheet to be folded projecting from each of the two sides of the group of products; ∘ a front side folding device for each of the two sides of the group of products to fold against each side a portion of the flaps of wrapping sheet, thus forming a front fold; ∘ a back side folding device for each of the two sides of the group of products to fold against each side a portion of the flaps of wrapping sheet, thus forming a back fold; ∘ a top side folding device for each of the two sides of the group of products to fold against each side a portion of the flaps of wrapping sheet, thus forming a top fold; ∘ a bottom side folding device for each of the two sides of the group of products to fold against each side a portion of the flaps of wrapping sheet, thus forming a bottom fold.
  14. The packaging machine of one or more of the previous claims, wherein the material, in which eddy currents can be induced, is ferromagnetic or paramagnetic material.
  15. The packaging machine of claims 1 and 14, wherein the tape (54A, 54B) is made of ferromagnetic material, preferably steel, iron or an alloy thereof; or the tape (54A, 54B) is made of, or includes, paramagnetic material, preferably aluminum or its alloys, the paramagnetic tape preferably containing an aluminum core or band of a thickness preferably between 5µm and 100 µm and more preferably between 20 µm and 25 µm, preferably the aluminum core or band providing, on the sealing surface (43A, 43B), a material, preferably Teflon, to facilitate the surface sliding on the products.

Description

Technical Field The present invention relates to the packaging machines for tissue paper products; more specifically, the object of the invention is a packaging machine for products, such as kitchen towel rolls and toilet rolls, wrapped in paper sheet. State of the Art In the paper industry, the paper products, particularly toilet rolls and kitchen towel rolls, are typically wrapped in sheets of thermoplastic film or, in the case of single rolls, in paper sheets. Packs containing a single roll are usually used for toilet rolls, while multi-roll packs, packaged with heat-sealable films, are used for both toilet rolls and kitchen towel rolls. Generally, the single-roll packs wrapped in paper film are not sealed, while larger packs, wrapped in thermoplastic film, are thermally sealed. To make these packs, the packaging machines have conveyors that, in the case of multi-roll packs, feed rows of rolls, arranged coaxially with one another with horizontal axis, to a station for grouping the rolls and forming a group of rolls arranged side by side in one or more layers. The groups of rolls are then conveyed to a vertically moving elevator that lifts each group of rolls to a wrapping station. The wrapping station wraps the group of rolls in a wrapping film, completing the pack of rolls. An example of these packaging machines is disclosed in the patent documents WO2009060490 and EP12289669B1. This type of packaging is called primary packaging and is that typically used for retail. The resulting packs are conveyed to the secondary packaging, where they are grouped and bagged in large plastic bags. Examples of these packaging machines are disclosed in EP1442984, EP1771335. Finally, the bags containing the packs are placed on pallets and sent to warehouses or shipped directly to distributors. In general, the groups of rolls are packaged by wrapping a thermoplastic wrapping film, such as polyethylene or other synthetic polymers, around a group of rolls, wrapping it around the four sides and forming a kind of parallelepiped with rectangular faces open on two opposite side faces. Then, the side flaps of the sheet projecting from the two side faces are folded, thus completing the covering of the rolls. Finally, the folds of the thermoplastic film are stabilized through heat-sealing made by heated Teflon-coated belts, as shown for example in EP1381543B1. In the case of single rolls to be packaged with paper sheets, the heated Teflon-coated belts heat-activate an adhesive, with which the sheets are pretreated on the whole surface. In the case of single rolls to be packaged, the sheets can also be stabilized without using glue. For example, in EP1518787B1, the stabilization of the sheet wrapped around the single roll is done by twisting the flaps projecting from the flat faces of the roll and pressing them into the core of the roll with a punch. In other cases, as described in EP2766266B1, the flaps projecting from the flat faces are partially folded in sequence and stabilized by pressing each partial fold into the core with a series of punches. Closing the single rolls without using glue has many disadvantages. The paper, twisted or folded several times and pressed into the core of the roll core is prone to tearing and breaking. In addition, not using glues makes the sealing very precarious, often causing the reopening of the package. Therefore, not only the quality of these packages is very low, but also the appearance thereof is compromised. The number of discarded packages is also very high because, once the wrapping sheet has been torn, the package must be discarded. One further major shortcoming of the prior art systems is the use of heated Teflon-coated belts, which are, as it is well-known, poorly energy-efficient. In addition, the Teflon-coated belts also have a very short useful life, as they shall be replaced very often. The very rapid wear of the Teflon-coated belts also results in high production variability because the efficiency of the belts drops dramatically in a short time, causing a lot of production waste. Moreover, in the case of packaging with paper sheet, the Teflon-coated belts are not efficient in transmitting heat to the glue that shall be reactivated; therefore, to achieve sufficiently acceptable sealing, the machine speed must be reduced, compromising productivity. As an alternative, it is necessary to heat the belts much more, thus shortening even more the useful life thereof and consuming more energy. A further disadvantage of the Teflon-coated belt is that it does not provide the roll with a uniform and sufficiently rigid contrast surface for sealing the folds of the wrapping sheet. Despite the greater problems in using a paper sheet instead of a classic thermoplastic film, high environmental awareness is increasingly pushing the paper industry toward the use of natural and recyclable materials, such as paper, instead of materials of a fossil nature, such as plastic heat-sealable films or synthet