WO2008107495A1

WO2008107495A1 - Vertical packing method and system

Info

Publication number: WO2008107495A1
Application number: PCT/ES2007/000125
Authority: WO
Inventors: Haritz Arrieta Aguirre; Lander DIAZ DE GUEREÑU OLABARRI; Jon Aguirre Arteaga; Francisco Jose Etxaniz Beaskoetxea; Roberto Oses Fisac
Original assignee: Ulma Packaging Technological Center, S. Coop.
Priority date: 2007-03-08
Filing date: 2007-03-08
Publication date: 2008-09-12

Abstract

The invention relates to a system and method for the vertical packing of products, including a feed tube (1) and longitudinal and transverse sealing means. The means (5) used for the transverse sealing of the film comprise ultrasound sealing means having opposing sealing surfaces (51, 52) that are configured to come into contact with the film tube (102) in order to perform the transverse sealing operation. Moreover, the longitudinal film sealing means and the transverse film sealing means are configured such that the longitudinal seal is provided at one end of the transverse seal.

Description

VERTICAL PACKAGING SYSTEM AND METHOD

TECHNICAL FIELD OF THE INVENTION

The invention encompasses in the field of vertical product packaging systems, for example, of products comprising liquid.

BACKGROUND OF THE INVENTION

At present, machines and installations for vertical bag forming are known for packaging - for example, unit or bulk - of products. In these systems it is based on a film that is sealed longitudinally to obtain a tube of film, which is divided into individual packages by means of transverse seals. A cut of the tube can be made in correspondence with the transverse seal, to separate a container from the next.

Such a system is reflected in WO-A-03/086869, which describes a machine in which a film is passed through a diverter or former, which directs the film on the periphery of a forming tube. Conveyor belts drag the film sheet down, while a sealing head performs a longitudinal seal, thus forming a tube of the film. On the other hand, a sealing and cutting head performs the transverse sealing of the tube, to form the base of the container and in turn cut an already formed lower container, so that it can be separated from the film tube. Next, the top container is filled through a central hole in the forming tube and subsequently the opening is closed. upper of said upper container by means of the sealing and cutting head.

In this type of systems different types of film can be used, depending on the needs that exist in each case, for example, depending on the type of product, depending on the characteristics of the filling process, etc.

Longitudinal and transverse sealing is carried out by applying pressure and heat (for example, using, in the case of transverse seals, cutting jaws with electrical resistors), and the elements can be controlled with pneumatic systems, with cam-based systems and motor, with servomotors, etc. Although these packaging systems may be useful for packaging many products, for example, for the packaging of bulk products (for example, for the packaging of seeds, nuts, etc.), they can present problems for packaging of liquid products or those comprising liquid, for example, food products that are stored in a liquid such as oil, etc. A problem is due to the fact that the liquid can splash the inner surfaces of the film tube, which makes it difficult or prevents the correct transverse sealing by heat sealing by applying pressure and heat in a conventional manner (for example, by means of resistance jaws with resistances electrical), since, for said sealing systems to work satisfactorily, the film surfaces to be joined should be clean (i.e. free of liquid splashes). Otherwise, the risk of defects in the transverse seal increases. Conventionally, for the packaging of many products, including products comprising liquids, horizontal feeding techniques have been used (for example, Thermoforming, Thermo-sealing, Flow-Pack, etc.), which can be very fast (since, at unlike what happens in vertical systems, in horizontal packaging systems the speed of product movement does not depend on gravity), but they are very expensive and / or require a lot of space. Therefore, for many applications, horizontal systems do not represent an adequate or optimal solution.

DESCRIPTION OF THE INVENTION A first aspect of the invention relates to a vertical product packaging machine or system, comprising: a feeding tube (which can be a substantially vertical tube through which the product to be packaged - which can comprise solid and / or liquid elements - moves by gravity); film feeding means (for example, similar to those described in WO-A-03/086869) configured to apply a film on said feeding tube, so that the film surrounds at least a part of said feeding tube and so that the film travels along at least a portion of said feed tube, towards an outlet end of said feed tube (for example, as in WO-A-03/086869); longitudinal sealing means of the film, configured to seal the film longitudinally by means of a longitudinal sealing, to form a tube of film that wraps at least a part of said tube of feeding (for example, in line with that described in WO-A-03/086869); and transverse sealing means of the film, configured to perform a transverse sealing of the film tube in a position posterior to the outlet end of said feeding tube (according to the film feed direction, that is, in a lower ^{^} position ' ¹ or "" lower ¹¹ to that of the outlet end of the feed tube, when the feed tube is positioned vertically for gravity feed of the product, in a conventional manner).

This transverse seal may constitute the base of a container and / or the "" upper closure "'of a previous container (ie, of a container that received its sealed base in a previous transverse sealing phase, and which has now been filled with the corresponding product and that must be closed in this next phase of transversal sealing).

In accordance with the invention, the transverse sealing means of the film comprise ultrasonic sealing means having opposite sealing surfaces configured to come into contact with the film tube to produce the transverse sealing. It has been proven that the use of ultrasonic welding sealing allows to overcome, at least to some extent, the problems caused by splashing of liquid on the inner surface of the film tube. Ultrasonic welding also works well to weld the film through drops and spots of liquid, since the vibrations displace the liquid, moving it away from the sealing area.

In this way, the invention allows the vertical packaging, by gravity, of liquid and / or oily products, sauces and mixed products (for example, solid products submerged in liquid or accompanied by liquid, such as cheese in oil) with a maximum reliability, despite the possible splashing of liquid on the inside of the film. In addition, the problems that the hot surfaces of conventional transverse sealing means (for example, heated by electrical resistors), and the corresponding problems of risk of packaging deterioration can be avoided. This system of the invention, based on the use of ultrasonic welding for, at least, transverse sealing, is also economical and, in addition, is not very demanding in terms of the cleaning conditions of the production environment.

Moreover, according to the invention, the longitudinal sealing means of the film and the transverse sealing means of the film are configured such that the longitudinal sealing is at one end of the transverse sealing. In this way, it is achieved that between the sonotrode and the anvil of the ultrasonic welding system, there are never more than two layers of film. Traditionally, as seen in WO-A-

03/086869, the realization of the longitudinal and transverse seal was made so that the longitudinal seal would remain in the central part of the transverse seal. In this way, in the area where both seals coincided, up to four layers of film were superimposed (on the one hand, the two layers to be joined and, on the other, the two layers that formed part of the longitudinal seal). In conventional processes, based on the use of jaws with electrical resistors, it seems that this did not represent a problem. However, in the case of ultrasonic welding, if it is desired to perform a transverse sealing of the tube, the fact that said sealing must be carried out, with the same tool, both on two layers of superimposed film as in an area where there are four overlapping layers (the area of four overlapping layers corresponds to the central area where the longitudinal weld is), making it very difficult to obtain homogeneous cross seals and increasing the risk of errors and defects in the sealing. To guarantee a good seal also in the area where four layers are superimposed, the power of the ultrasound system should be increased, with the drawbacks that this implies. In addition, if the sealing has to be done on a non-homogeneous object (that is, with a thickness that varies from two layers to four layers of film), it is more difficult to obtain a homogeneous result.

The longitudinal sealing means of the film can be configured to perform the longitudinal sealing so that two areas of the same face or surface of the film are joined. For example, when the tube is formed, the "inner" surfaces of two ends or longitudinal edges of the film can be joined, so that a longitudinal weld is established in which the free longitudinal ends or edges of the film are juxtaposed, directed "^'' out '' ¹ of the tube. In this way, a very homogeneous surface is achieved on which the transverse sealing is then performed. That is, the longitudinal sealing means of the film can be configured such that said two areas of the same film surface is joined near respective longitudinal edges of the film, so that a longitudinal weld is created in correspondence with said longitudinal edges.

The system can be configured so that in the area of the transverse seal, there is no area with more than two layers of film superimposed. The system may additionally comprise stretching means configured to stretch the film tube in correspondence with said sealing surfaces. These stretching means (which can be pneumatically operated, for example) can comprise at least two tweezers configured to stretch the film tube in opposite directions (for example, substantially horizontal) and / or so that the film tube is substantially flat in a direction parallel to the transverse sealing surfaces. The pliers may comprise at least two pairs of pliers that each comprise a clamp located higher than the sealing surfaces and a clamp located lower than said sealing surfaces (when the feeding tube is arranged vertically, that is, in the usual operating position of this type of system).

Using this type of stretching subsystem, wrinkles can be avoided and a substantially flat surface can be established for transverse sealing, which serves to reduce the risk of welding defects.

On the other hand, in order to be able to establish an at least partial vacuum in the package, the described system may additionally comprise a suction subsystem for removing air and, optionally, part of a product from a package (for example, part of a liquid product) before transverse sealing of the container. This suction subsystem may comprise at least one suction tube that can extend through the feed tube and protrude through the outlet end of the feed tube, extending toward a point lower than said outlet end (when the feed tube is arranged vertically, in its usual operating position). In addition, the suction subsystem may comprise a shutter subsystem (which may comprise, for example, two activated traders pneumatically) configured to exert pressure on the film tube and ^"" close it "in a position between the outlet end of the feed tube and a suction end of the suction tube (or tubes), to hinder the entry of air in the container from the outside, during the phase of suction of air through the suction tubes, that is, during the phase of elimination of air from the container prior to the lock thereof by the transverse seal. or the suction tubes) may end up in a position higher than the transverse sealing surfaces, so as not to interfere with the transverse sealing

(In this way, it is not necessary to remove the suction tubes before transverse sealing, which simplifies the system).

On the other hand, in correspondence with the outlet end of the feeding tube there may be two or more stretching rods configured to deflect the film tube transversely in two opposite directions, to initiate a flattening of the film tube. These rods can be fixed or pneumatically activated, and can be located in correspondence with the suction tubes.

On the other hand, there may be a compaction subsystem comprising two opposite plates (which can be pneumatically operated) configured to exert pressure on the film tube at a position lower than the transverse sealing surfaces, when the feed tube is arranged vertically The system can be configured to feed the film and to perform transverse sealing in a synchronized manner with a feeding of products by the feeding tube, so that each product to be packaged is housed in a bag defined by the film tube and with a base defined by a transverse seal of the film tube. In addition, the system may be - S -

configured to feed the film after having received a product to be packaged on said sealed base, and before a new transverse sealing of the film tube, so that said transverse sealing is made above the product, determining a new sealed base on the that you can deposit the next product to be packed.

Another aspect of the invention relates to a method of vertical product packaging, comprising the steps of: applying a film on a feeding tube and forming a film tube from said film by means of a longitudinal sealing; Sequentially perform a product feed through the feed tube and a transverse seal of the film tube, to produce packages comprising portions of film tube sealed with the transverse seal and containing the corresponding product. According to the invention, transverse sealing is performed by ultrasound. In addition, the longitudinal sealing of the film and the transverse sealing are carried out so that the longitudinal sealing is at one end of the transverse sealing. What has been described regarding the system is also applicable to the method, mutatis mutandis.

The method may, for example, comprise the following steps that are carried out after the entry of the product to be filled into a portion of the film tube, through the feed tube, and before a vertical seal is made to close said portion. of the film tube above the product:

- compact the product by pressure with plates;

- sucking air and, optionally, a portion of the product contained in the portion of the film tube; Y - stretch the film tube with tweezers to facilitate a substantially flat area for transverse sealing application.

Prior to air suction, pressure can be applied on the film tube to hinder the entry of air into the part of the film tube portion that contains the product.

DESCRIPTION OF THE FIGURES To complement the description and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical implementation thereof, a set of figures is accompanied as an integral part of the description in which, as an illustration and not limitation, the following has been represented:

Figures 1-4.- Show schematic elevational views of the system according to a preferred embodiment of the invention, in four successive operational phases.

Figures 5-6.- You show two schematic views of the film tube, with longitudinal sealing (figure 5) and longitudinal and transverse sealing (figure 6).

Figures 7-10.- Samples viewed in perspective of different components or subsystems of the apparatus or system of the invention.

Figure 11.- Shows a perspective view of the machine or system of the invention.

Figures 12 and 13.- Shows two side elevation views of the machine or system of the invention (one of the views reflects the system rotated 90 ° around a vertical axis with respect to the other view). PREFERRED EMBODIMENT OF THE INVENTION

Figures 1-4 reflect various moments of the operation of a system according to a preferred embodiment of the invention. As can be seen, the system comprises a feeding tube 1 and film feeding means (which can come from a film reel and pass through trainers 2 to be applied on the feeding tube, and then be dragged down , that is, towards the outlet end 11 of the feed tube, by means of a drag system 3 with its corresponding drag belts), for example, in the same way as in WO-A-03/086869. In addition, as in WO-A-03/086869, there are means 4 for longitudinal sealing of the film that can be of any conventional type (for example, based on electrical resistors) and which are configured to seal the film longitudinally by sealing longitudinal 100 (see figures 5 and 6), to form a film tube 102 that wraps at least a part of the feeding tube 1. On the other hand, there are the means 5 of transverse sealing of the film, configured to make successive transverse seals 101 (see Figure 6) of the film tube 102 in a position posterior to the outlet end 11 of the feed tube 1, that is, below the outlet end 11. These transverse sealing means 5 comprise sealing means by ultrasounds having opposite sealing surfaces 51 and 52, which, as is conventional in ultrasonic sealing systems, may comprise an anvil (corresponding to one of the sealing surfaces 52) and a sonotrode (corresponding to the other sealing surface 51), which, conventionally, can be activated from a generator of an electrical signal with the appropriate frequency (for example, in the order of 15-40 kHz), a converter that converts the electrical signal in a mechanic and a booster. These equipments are conventional and the average expert in the field can easily choose the one that best suits a specific application, depending on, for example, the characteristics of the materials to be welded and other aspects such as, for example, the cost of the equipment.

As can be seen in Figures 5 and 6, the longitudinal sealing means of the film and the transverse sealing means of the film are configured so that the longitudinal sealing is at one end of the transverse sealing. In the illustrated embodiment (see Figures 5 and 6), the longitudinal sealing is performed so that two areas of the same surface of the film are joined and so that these two areas are joined near respective longitudinal edges of the film. In this way, a longitudinal weld is created in correspondence with the longitudinal edges, and in the transverse seal 101 there is no area with more than two layers of film superimposed, as can be seen in Figures 5 and 6. Of this Thus, a reliable cross closure can be achieved by ultrasonic welding.

To facilitate transverse sealing and avoid wrinkles etc. in the film in the sealing zone (something that could damage the quality of the sealing), stretching means 6 are provided which are illustrated in more detail in Figure 7 (see also Figures 11 and 13) and comprising two pairs of pliers (61, 62) configured to stretch the film tube in correspondence with the sealing surfaces (51, 52) of the transverse sealing means, in substantially horizontal opposite directions (when the feeding tube is in its vertical operating arrangement ), so that the film tube 102 is substantially flat in a direction parallel to the sealing surfaces. Each pair of pliers comprises a clamp located higher than the sealing surfaces and a clamp located lower than the sealing surfaces. The clamps are pneumatically actuated and configured to grip the film tube and to stretch it in opposite directions, so that the film tube is substantially flat in the area where the transverse seal occurs.

On the other hand, according to this preferred embodiment of the invention, the packaging system additionally comprises a suction subsystem for removing air and, optionally, part of a product (for example, a liquid product) from a package before transverse sealing of the package, that is, to produce a vacuum at least partially in the package, something that can serve to improve the preservation of the product. This suction subsystem comprises in this case two suction tubes 71 (see Figures 1-4, 11-13 and, especially, 8) which extends through the feeding tube 1 and protrudes through the outlet end 11 of the tube of feeding. These suction tubes are connected to a suction device (not shown) that can be of any conventional type. It is not considered necessary to describe it here in more detail.

In order to improve the operation of the suction subsystem, a sealing subsystem 73 with two shutters 731 (basically, treadmills with flexible contact surface) (see, for example, Figures 1-4 and 9) which are pneumatically activated and which are pneumatically activated they are configured to exert pressure on the film tube in a position between the outlet end 11 of the feed tube and the suction ends 711 of the suction tubes 71, crushing it to prevent or hinder the entry of air. In this way, the entry of air into the package from the outside is difficult, during the air suction phase through the suction tubes 71 and before the transverse sealing. As can be seen in the figures, the suction tubes terminate in a position higher than the sealing surfaces (51, 52) of the transverse sealing means, so that they do not obstruct the transverse ultrasonic sealing.

As can be seen in Figure 8, in correspondence with the outlet end 11 of the feeding tube, two stretching rods 8 are arranged which serve to deflect the film tube transversely in two opposite directions. This serves to initiate a flattening of the film tube, which facilitates the subsequent actuation of the stretching tongs (61, 62), and / or to facilitate packaging.

A compaction subsystem is also provided, comprising two opposite plates 9 (see, for example, figures 9 and 12), pneumatically operated, and which serve to exert pressure on the film tube below the sealing surfaces (51 , 52) of the transverse sealing means 5. In this way, the product can be compacted and / or reorganized before the transverse seal that superiorly closes the container occurs, and reduces, for example, the risk of air pockets remaining inside the package.

In this embodiment of the invention, the system is configured to feed the film and to perform the transverse sealing in a synchronized manner with a product feed by the feeding tube 1, so that each product - or part of the product - to be packaged is it is housed in a bag defined by the film tube and with a base defined by a transverse seal of the film tube. After a product to be packaged has been received on the sealed base, the film is fed and a new transverse seal is made above the product, determining a new sealed base on which the next product to be packaged can be deposited. The system can operate according to the following method or sequence of steps:

The film is applied to the tube and fed in a conventional manner, with a longitudinal weld or seal 100 that establishes a film tube 102. The transverse seals 101 are produced by ultrasonic welding, and each package 103 is closed by the longitudinal seal. 100 and by two transverse seals 102, as seen in Figures 5 and 6.

Once a transverse seal has been made, this transverse seal serves as the "base" of a new package, the product 200 is introduced through the feed tube, as can be seen in Figure 1, in which look at the product 200 deposited in the lower part of the film tube, closed inferiorly by a transverse seal.The traders 731 are in their removed position, just like the compaction plates 9. Next, the compaction plates 9 approach each other and there is a compaction and / or a reorganization / reconfiguration of the product 200. At the same time

(or later) the footsteps 731 of the shutter subsystem 73 also approach, pressing on opposite walls of the film tube to hinder the entry of air from above. This phase of the process is reflected in Figure 2.

Next, the suction of air (and, optionally, a part of the product) is activated through the suction tubes 71. Since the footsteps 731 prevent or hinder the entry of air from above, a vacuum occurs (at least partial) inside the film tube under said treadmills (this phase can be seen in figure 3). Now you can activate the stretching clamps (61, 62), which grip respective parts of the tube (already crushed by the pressure of the outside air against the internal partial vacuum) and throw them out, in opposite directions, to avoid wrinkles that could make cross sealing difficult. Subsequently, the sealing surfaces (51, 52) of the anvil and sonotrode approach each other and come into contact with the film tube, to produce the transverse seal in the corresponding area.

Properly sealed containers can then be separated from the rest of the film tube in a conventional manner.

In this text, the word "comprises" and its variants (such as "understanding", etc.) should not be construed as excluding, that is, they do not exclude the possibility that what is described includes other elements, steps, etc.

On the other hand, the invention is not limited to the specific embodiments that have been described but also covers, for example, the variants that can be made by the average person skilled in the art (for example, in terms of the choice of materials, dimensions , components, configuration, etc.), within what follows from the claims.

Claims

1.- Vertical product packaging system, comprising: a feeding tube (1); film feeding means (2, 3) configured to apply a film on said feeding tube, so that the film surrounds at least a part of said feeding tube and so that the film travels along at least a part of said feed tube, towards an outlet end (11) of said feed tube; means (4) for longitudinal sealing of the film, configured to seal the film longitudinally by means of a longitudinal sealing (100), to form a film tube (102) that wraps at least a part of said feeding tube (1); means (5) for transverse sealing of the film, configured to perform a transverse sealing (101) of the film tube (102) in a position posterior to the outlet end (11) of said feed tube (1), in the direction film feed; characterized in that the transverse sealing means (5) of the film comprise ultrasonic sealing means having opposite sealing surfaces (51, 52) configured to come into contact with the film tube

(102) to produce the transverse seal; and because the longitudinal sealing means of the film and the transverse sealing means of the film are configured so that the longitudinal sealing is at one end of the transverse sealing.

2. System according to claim 1, wherein the longitudinal sealing means of the film are configured to perform the longitudinal sealing of so that two areas of the same surface of the film are joined.

3. System according to claim 2, wherein the longitudinal sealing means of the film are configured so that said two areas are joined near respective longitudinal edges of the film, so that a longitudinal weld is created in correspondence with said edges Longitudinal

4. - System according to any of the preceding claims, configured so that in the transverse seal (101), there is no area with more than two layers of film superimposed.

5. - System according to any of the preceding claims, which additionally comprises stretching means (6) configured to stretch the film tube in correspondence with said sealing surfaces (51, 52) of the transverse sealing means (5).

6. System according to claim 5, wherein said stretching means comprise at least two tweezers (61, 62) configured to stretch the film tube in substantially horizontal opposite directions.

7. System according to claim 6, wherein said tweezers (61, 62) are configured to stretch the film tube so that the film tube (102) is substantially flat in a direction parallel to the sealing surfaces ( 51, 52).

8. System according to any of claims 6-7, wherein said at least two clamps (61, 62) comprise at least two pairs of clamps, each pair of clamps comprising a clamp located higher than the sealing surfaces (51, 52) and a clamp located lower than said sealing surfaces.

9. System according to any of claims 5-8, wherein said stretching means (6) are pneumatically actuated.

10. System according to any of the preceding claims, which additionally comprises a suction subsystem for removing air and, optionally, part of a product from a package before the transverse sealing of the container, said suction subsystem comprising at least one suction tube (71) extending through the feeding tube (1) and protruding through the outlet end (11) of the feeding tube, extending towards a point lower than said outlet end.

11. System according to claim 10, wherein said suction subsystem further comprises a sealing subsystem (73) configured to exert pressure on the film tube in a position between the outlet end

(11) of the feeding tube and a suction end

(711) of said, at least one, suction tube (71), to hinder the entry of air into the container from the outside, during an air suction phase through said, at least one, suction tube ( 71).

12. System according to claim 11, wherein said shutter subsystem comprises two pneumatically operated treadmills (731).

13. System according to any of claims 10-12, wherein said at least one suction tube (71) ends (711) in a position higher than the sealing surfaces (51, 52) of the sealing means transversal (5).

14. - System according to any of the preceding claims, wherein at least two stretching rods (8) configured to deflect the film tube transversely in two directions are arranged in correspondence with the outlet end (11) of the feed tube. opposite, to start a flattening of the film tube.

15. - System according to any of the preceding claims, which additionally comprises a compaction subsystem comprising two opposite plates (9) configured to exert pressure on the film tube in a position lower than the sealing surfaces (51, 52) of the transverse sealing means (5).

16. System according to claim 15, wherein said plates (9) are pneumatically operated.

17. System according to any of the preceding claims, configured to feed the film and to perform the transverse sealing, in a synchronized manner with a feed of products by the feeding tube (1), so that each product to be packaged is housed in a bag defined by the film tube and with a base defined by a transverse seal of the film tube.

18. System according to claim 17, configured to feed the film after having received a product to be packaged on said sealed base, and prior to a transverse seal of the film tube, so that said transverse seal is made above the product , determining a new sealed base on which the next product to be packaged can be deposited.

19.- Method of vertical packaging of products, comprising: applying a film on a feeding tube (1) and forming a film tube (102) from said film by means of a longitudinal seal (100), - performing sequentially , a product feed through the feed tube (1) and a transverse seal (101) of the film tube (102), to produce packages (103) comprising portions of film tube sealed with the transverse seal (102) and that contain the corresponding product; characterized in that the transverse sealing is performed by ultrasound; and because the longitudinal seal (100) of the film and the transverse seal (101) of the film are performed so that the longitudinal seal (100) is at one end of the transverse seal (101).

20. Method according to claim 19, wherein the longitudinal sealing is carried out so that two areas of the same surface of the film are joined.

21. Method according to claim 20, wherein said two areas are joined near respective longitudinal edges of the film, so that a longitudinal weld is created in correspondence with said longitudinal edges.

22. Method according to any of claims 19-21, wherein the longitudinal seal and the transverse seal are performed such that in the transverse seal (101), there is no area with more than two layers of film superimposed.

23. Method according to any of claims 19-22, which additionally comprises the step of stretching the film tube in correspondence with sealing surfaces (51, 52) before performing the transverse sealing with said sealing surfaces (51, 52 ).

24. Method according to claim 23, in the step of stretching the film tube is performed by stretching the film tube with at least two tweezers (61, 62), in substantially horizontal opposite directions.

25. The method according to claim 24, wherein the film tube is stretched so that it is substantially flat in a direction parallel to sealing surfaces (51, 52) of sealing means (5) for transverse sealing.

26.- Method according to any of claims 19-25, which additionally comprises the passage of sucking air and, optionally, part of a product of a container in formation before transverse sealing, by means of at least one suction tube (71) which It extends through the feed tube (1) and protrudes through an outlet end (11) of the feed tube.

27. A method according to claim 26, wherein to facilitate the removal of air in the container by suction of air, pressure is exerted on the film tube in a position between the outlet end (11) of the feed tube and a suction end (711) of said at least one suction tube (71).

28.- Method according to any of claims 19-

27, which additionally comprises the step of, before producing the transverse sealing of the film tube, initiating a flattening of the film tube by at least two stretching rods (8) located in correspondence with an outlet end (11) of the feeding tube.

29.- Method according to any of claims 19-28, which additionally comprises the step of, before carrying out the transverse sealing of the film tube corresponding to a container, compacting the contents of the package by means of two opposite plates (9) configured to exert pressure on the film tube.

30.- Method according to any of claims 19-29, comprising the following steps that are performed after the entry of the product to be filled in a portion of the film tube (102), through the feed tube, and before that a vertical seal (101) be made to close said portion of the film tube above the product:

- compact the product by pressure with plates

(9); - sucking air and, optionally, a portion of the product contained in the portion of the film tube, -

- stretch the film tube with tweezers (61, 62) to facilitate a substantially flat area for transverse sealing application.

31. Method according to claim 30, in which prior to the air suction, pressure is applied on the film tube to hinder the entry of air into the part of the film tube portion that contains the product.

32.- Method according to any of claims 19-31, wherein the feeding of the film and the transverse sealing are carried out synchronously with the feeding of products by the feeding tube (1), so that each product to be packaged stays in a bag defined by the film tube (102) and with a base defined by a transverse seal (101) of the film tube.

33. Method according to claim 32, wherein the film is fed after having received a product to be packaged on said sealed base (101), and prior to a transverse seal (101) of the film tube, so that said Transverse sealing (101) is made above the product, determining a new sealed base on which the next product to be packaged can be deposited.