Control method for a vertical packaging machine and vertical packaging machine

Abstract

The invention relates to a method and a machine (100) for vertical packaging of products (P). The method comprises a compression stage comprising a tapping step in which said product (P) is tapped from the outside of said film tube (3); a stream generating step following the tapping step, in which said product (P) is pushed in a downward direction from the inside of said film tube (3) by a gas stream; and a pressing step starting after the start of the stream generating step, in which the film tube (3) is pressed from the outside in a transverse direction to a forward direction of the product (P).

Description

TECHNICAL FIELD

[0001] The present invention relates to control methods for vertical packaging machines, and to vertical packaging machines.PRIOR ART

[0002] A vertical packaging machine comprises a hollow forming tube with a longitudinal axis, an inlet and an outlet downstream of the inlet. The longitudinal axis may be vertical or may be inclined with respect to the vertical.

[0003] The forming tube is configured to receive a continuous film on the outside, to give a tubular shape to said film, and to receive the products to be packaged through the inlet. The products pass through the inside of the forming tube and exit the forming tube through the outlet. The shape of the forming tube may vary depending on the package to be packaged.

[0004] A vertical packaging machine further comprises a longitudinal sealing assembly for longitudinally sealing the longitudinal edges of the tubular shaped film surrounding the forming tube, thereby generating a film tube, and a transversal actuation assembly downstream of the forming tube, for cutting the film tube transversely with respect to the longitudinal axis of the forming tube and for sealing said film tube on both sides of the cut, when said transversal actuation assembly is arranged in a closed position. The operation of the transversal actuation assembly results in a film tube closed at one end upstream of the cut and in a package closed at both ends downstream of the cut. The product delivered through the forming tube reaches the closed end of the film tube and will form part of the package generated as a result of the subsequent actuation of the transversal actuation assembly.

[0005] When a product to be packaged consists of herbs (parsley, mint, coriander, etc.), vegetable leaves (lettuce, spinach, etc.), chopped vegetables or snacks for example, which comprise light parts, once said parts reach the inside of the film tube they are distributed unevenly and may, for example, occupy a larger volume and may then affect the transversal sealing or require a larger amount of packaging film which would result in a larger package size.

[0006] CN216509217U discloses a device for tapping the bottom of the film tube containing the product to distribute the product more evenly throughout the film tube to ensure that no parts of the product to be packaged interfere with the transverse sealing.DISCLOSURE OF THE INVENTION

[0007] The object of the invention is to provide a control method for a vertical packaging machine, and a vertical packaging machine, as defined in the claims.

[0008] The method comprises a product feeding stage in which a product to be packaged is placed inside a film tube; a displacement stage in which the film tube is caused to advance in a downward direction such that at least part of the film tube is disposed downstream of a transversal actuation assembly; and a transversal sealing and cutting stage in which the film tube is transversely sealed and cut by the transversal actuation assembly, resulting in a film tube with a closed end upstream of the transversal cut and in a package with the packaged product inside downstream of the transversal cut.

[0009] The method further comprises a compression stage which is performed with at least part of the product disposed downstream of the transversal actuation assembly.

[0010] The compression stage comprises a tapping step in which the closed end of the film tube is tapped at least once from the outside of the film tube, in such a way as to cause said product to move in an upward direction within the film tube; a stream generator step following the tapping step, in which said product is pushed in a downward direction from the inside of said film tube by a downward gas stream; and a pressing step starting after the start of the injection step, in which the film tube is pressed from the outside in a direction transverse to the forward direction of the product and downstream of the transversal actuation assembly, such that some of the gas inside the film tube downstream of the transversal actuation assembly is displaced in an upward direction.

[0011] Preferably the product to be packaged is a product consisting of multiple parts, such as pieces of foodstuffs like lettuce leaves, spinach, parsley, mint, coriander, or snacks, for example.

[0012] The compression stage of the method makes possible to fit more product into a package of the same size or smaller than in the prior art, or to fit the same amount of product as in the prior art into a smaller package. By squeezing a larger amount of product into a smaller space and optimising the use of the volume of the package, at least the following advantages are obtained: reducing the amount of film required for each package, the cost of the package being reduced; increasing the number of packages that can be stored in the same space, reducing the logistics required; and transporting a larger number of packages in the same space for transport, which also reduces the transport cost.

[0013] The tapping step allows the product to be repositioned inside the film tube, especially when the product is made up of pieces of herbs or vegetables such as lettuce leaves, parsley or similar, thus changing the distribution of the product and obtaining a more homogeneous distribution. Combining the tapping step with the stream generator step also causes the product to be compacted inside the film tube, which makes it possible to obtain a package with more product in the same volume or the same product in a smaller volume. The pressing step also helps to evacuate the gas introduced into the film tube during the stream generating step by evacuating it upwards (above the transversal actuation assembly), thus further reducing the volume of the pack.

[0014] The transversal sealing and cutting of the film tube by the transversal actuation assembly is performed after completion of the compression stage, or during the pressing step of the compression stage, thereby reducing the risk for the product to be entrapped by the transversal actuation assembly during the sealing and cutting step, and the final package generated (part of the film tube downstream of the transversal actuation assembly and physically separated from the film tube upstream of the transversal actuation assembly after such operation of the transversal actuation assembly) is made smaller and / or contains more product, the product is compacted, and the package is prevented from having the appearance of being swollen.

[0015] These and other advantages and features of the invention will become apparent in view of the figures and the detailed description of the invention.DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 shows a front view of an embodiment of a vertical packaging machine according to the invention. Figure 2 shows the machine of figure 1, implementing a tapping step according to an embodiment of the method of the invention. Figure 3 shows the machine of figure 1, implementing a stream generating step according to an embodiment of the method of the invention. Figure 4 shows the machine of figure 1, implementing a pressing step according to an embodiment of the method of the invention. DETAILED DISCLOSURE OF THE INVENTION

[0017] A first aspect of the invention relates to a control method adapted to be implemented in a vertical packaging machine 100. The method comprises: a film supply stage in which a film is supplied around a forming tube 1 of the machine 100; a longitudinal sealing stage in which two longitudinal ends of the film arranged around the forming tube 1 are sealed together by means of a longitudinal sealing assembly of the machine 100 not shown in figures, a film tube 3 being generated; a product feeding stage in which a product P to be packaged is fed into the film tube 3 from the inside of the forming tube 1; a displacement stage in which the film tube 3 is caused to advance in a downward forward direction A such that at least part of the product P inside the film tube 3 is disposed downstream of a transversal actuation assembly 4; and a transversal sealing and cutting stage in which said film tube 3 is transversely sealed and cut downstream of the forming tube 1, by means of the transversal actuation assembly 4 of the machine 100, a film tube 3 with a closed end upstream of the transversal cut and a package with the packaged product P downstream of said transversal cut being generated.

[0018] The method further comprises a compression stage which is executed with at least part of said product P downstream of the transversal actuation assembly 4. The compression stage comprises at least one tapping step (see figure 2), one stream generating step (see figure 3) and one pressing step (see figure 4) which will be described in the following. The transversal sealing and cutting stage is executed after the end of the compression stage, or during the pressing step of the compression stage.

[0019] In the tapping step, the closed end of the film tube 3 is tapped from the outside of the film tube 3, at least once, and the tapping is carried out in such a way that the product P is displaced in an upward direction inside the film tube 3. Due to the effect of gravity, the product P tends to return towards the closed end of the film tube 3 once it has reached a certain height (which depends on the force of the tapping), so that the distribution of the product P is modified and it is redistributed more homogeneously and occupies a smaller volume inside the film tube 3 once the tapping stage has been completed.

[0020] The stream generating step follows the tapping step, and in said stream generating step the product P is pushed in a downward direction in the inside of the film tube 3 with a gas stream (preferably air). In this method the product P does not passively return to the closed end of the film tube 3 but is actively pushed by the said pushing. Preferably the stream generating step takes place while at least part of the product P is in suspension after a tapping, i.e. before the entire product P is again disposed on the end of the film tube 3 after the tapping step. Preferably, in the downward stream generating step, a gas stream is injected into the film tube 3 in the form of a blow and at such a speed that the so-called Venturi effect is generated whereby atmospheric air is sucked upstream of the gas injection area, resulting in the downward gas stream which pushes the product P. The flow of the downward stream gas is greater than the flow of the injected gas, due to that said downward stream is composed by the injected gas plus the sucked atmospheric air. This allows a faster and more efficient pushing of the product P. To generate the Venturi effect, a stream generator 7, adapted to be connected to a gas source, can be used, which receives the injected gas and distributes it in an appropriate manner towards the film tube 3. Such a stream generator 7 is described in more detail in the applicant's own documents EP3530575A1 and EP3718909A1 ("injection device 3"), which are incorporated by reference for these purposes.

[0021] The pressing step begins after the start of the stream generating step, and in this pressing step the film tube 3 is pressed from the outside in a direction transverse to the forward direction A of the product P and downstream of the transversal actuation assembly 4, so that part of the gas inside the film tube 3 downstream of the transversal actuation assembly 4 is displaced in an upward direction, resulting in a package.

[0022] The transversal sealing and cutting of the film tube 3 by means of the transversal actuation assembly 4 takes place after the start of the pressing step. This sealing and cutting can be carried out during the pressing step or after the end of the pressing step (in the latter case it would therefore be carried out after the compression stage). During the sealing and cutting, in addition, the injection of a gas stream starting in the stream generating step can be maintained or, preferably, said injection is terminated before said sealing and cutting.

[0023] Preferably, in the tapping step the closed end of the film tube 3 is tapped with a tapping device 5 comprising a tapping member 5.0 which physically contacts said film tube 3 on the outside and downstream of the transversal actuation assembly 4, or said closed end of the film tube 3 is tapped by means of an injection of pressurised air against said film tube 3, the tapping device 5 comprising an injector not shown in the figures in this latter case. In any of these options an upward displacement of said product P is caused as a result of the tapping, which causes the redistribution of said product P inside the film tube 3.

[0024] During the tapping step the product P can be tapped only once, but it can also be tapped a plurality of times, intermittently. In the latter case, depending on the desired effect on the product P or the type of product P to be packaged, the taps could be generated by vibration of the tapping member 5.0 or another specific element.

[0025] In the pressing step, the pressure is preferably generated with a pressing device 6 comprising a first pressing member 6.1 and a second pressing member 6.2 facing each other and arranged downstream of the transversal actuation assembly 4, the film tube 3 being arranged between said pressing member 6.1 and 6.2 when the film tube 3 is caused to move forward in the forward direction A. Said pressing members 6.1 and 6.2 are configured to, in operation, physically contact the outside of the film tube 3 when approaching each other, thus pressing and compacting the part of the film tube 3 which preferably will result in the final packaging.

[0026] A second aspect of the invention relates to a vertical packaging machine which is adapted to implement the method of the first aspect of the invention, in any of its embodiments and / or configurations.

[0027] The machine 100 comprises a forming tube 1 configured to receive a film and to give it a tubular shape; a longitudinal sealing assembly configured to generate a film tube 3 by sealing together two longitudinal ends of the tubular shaped film; and a transversal actuation assembly 4 arranged downstream of the forming tube 1 and configured to transversely seal and cut the film tube 3.

[0028] The machine 100 further comprises a tapping device 5 which is arranged downstream of the transversal actuation assembly 4 and which is configured to tap the film tube 3 from the outside and in an upward direction; a stream generator 7 configured to generate a gas stream pushing at least part of the product P arranged inside the film tube 3; and a pressing device 6 for, downstream of the transversal actuation assembly 4, pressing the film tube 3 from the outside in a transverse direction.

[0029] The tapping device 5 comprises a tapping member 5.0 which physically contacts the closed end of the film tube 3 downstream of the transversal actuation assembly 4 when actuated, or an injector (not depicted in the figures) to generate an injection of pressurised air against the film tube 3.

[0030] In the case where the tapping device 5 comprises a tapping member 5.0, in some embodiments said tapping device 5 comprises an actuator 5 configured to cause said tapping member to vibrate, to intermittently tap the film tube 3.

[0031] In other embodiments the tapping device 5 may also be configured to tap the film tube 3 intermittently, although not by vibration.

[0032] The stream generator 7 is configured to inject a gas in a downward direction towards the inside of the film tube 3 in such a way that a downward gas stream is generated by said injection, which pushes and compacts the product P, by the well-known Venturi effect as described for the first aspect of the invention. The stream generator 7 is adapted to be connected to a gas source and distributes said gas in a suitable manner towards the film tube 3 to generate the Venturi effect. A stream generator 7 of this type is described in more detail in the applicant's own documents EP3530575A1 and EP3718909A1 ("injection device 3"), which are incorporated by reference for these purposes.

[0033] In some embodiments, gas is introduced into the film tube 3 from upstream of the film tube 3 in a conventional manner. In other embodiments, the forming tube 1 may be a coaxial forming tube formed by two concentric tubes between which a gap is defined, and gas is introduced in the tube film 3 through the gap.

[0034] The pressing device 6 comprises a first pressing member 6.1 and a second pressing member 6.2 facing each other and arranged downstream of the transversal actuation assembly 4, the film tube 3 being disposed between said pressing members 6.1 and 6.2 when the film tube 3 is caused to advance in the forward direction A. Said pressing members 6.1 and 6.2 are configured to, in operation, physically contact the outside of the film tube 3 when approaching each other, they displacing the air inside the film tube 3 with their actuation, and thus the product P inside the part of the film tube 3 which will be a package being compacted.

[0035] The transversal actuation assembly 4 comprises a first tool 4.1 and a second tool 4.2 between which the film tube 3 moves in the forward direction A, and said tools 4.1 and 4.2 move relative to each other to seal and cut said film tube 3 in such a way as to clamp said film tube 3 together. Preferably the pressing device 6 is attached to the transversal actuation assembly 4 and moves together with said transversal actuation assembly 4. In particular the first pressing member 6.1 is attached to the first tool 4.1 and moves in conjunction with said first tool 4.1, and the second pressing member 6.2 is attached to the second tool 4.2 and moves together with said second tool 4.2.

[0036] The machine 100 comprises a control unit 8 communicated with at least the transversal actuation assembly 4, the tapping device 5 and the stream generator 7 (in the embodiments where the pressing device 6 is attached to the transversal actuation assembly 4), the control unit 8 being configured to coordinate the actuations between said transversal actuation assembly 4, said tapping device 5 and said stream generator 7 to implement the compression stage according to the method of the first aspect of the invention in any of its embodiments and / or configurations.

[0037] In embodiments where the pressing device 6 is not attached to the transversal actuation assembly 4, the control unit 8 is communicated with said pressing device 6 and configured to coordinate the actuations between said transversal actuation assembly 4, the tapping device 5, said pressing device 6 and the stream generator 7 to implement the compression stage according to the method of the first aspect of the invention in any of its embodiments and / or configurations.

Claims

1. Control method for a vertical packaging machine, the method comprising at least one product feeding stage in which a product (P) to be packaged is arranged inside a film tube (3); a displacement stage in which the film tube (3) is caused to advance in a downward forward direction (A) such that at least part of said product (P) is arranged downstream of a transversal actuation assembly (4); and a transversal sealing and cutting stage wherein said film tube (3) is transversely sealed and cut by said transversal actuation assembly (4), a film tube (3) with a closed end upstream of the transversal cut and a package with the packaged product (P) downstream of said transversal cut being generated, characterised in that the method further comprises a compression stage which is executed while at least part of the product (P) is placed downstream of the transversal actuation assembly (4), the compression stage comprising a tapping step in which the closed end of the film tube is tapped at least once from the outside of the film tube (3) in such a way as to cause said product (P) to move in an upward direction inside the film tube (3); a stream generating step following the tapping step, wherein said product (P) is pushed in a downward direction from inside said film tube (3) by means of a downward gas stream; and a pressing step starting after the start of the stream generating step, in which the film tube (3) is pressed from the outside in a direction transverse to the forward direction (A) of the product (P) and downstream of the transversal actuation assembly (4), in such a way that part of the gas inside the film tube (3) downstream of the transversal actuation assembly (4) is displaced in an upward direction, the transversal sealing and cutting stage being carried out after completion of the compression stage or during the pressing step of the compression stage.

2. Control method according to claim 1, wherein in the tapping step, the closed end of the film tube (3) is tapped with a tapping device (5) comprising a tapping member (5.0) which physically contacts the film tube (3) downstream of the transversal actuation assembly (4), or said closed end of the film tube (3) is tapped by an injection of air against said film tube (3).

3. Control method according to claim 1 or 2, wherein in the tapping step, the product (P) is tapped a plurality of times intermittently.

4. Control method according to any of claims 1 to 3, wherein the stream generating step starts while at least part of the product (P) is in suspension due to the tapping step or after said product (P) finishes being in suspension.

5. Control method according to any of claims 1 to 4, wherein in the stream generating step, the gas is injected in a downward direction towards the interior of the film tube (3), in such a way that say gas injection causes the suction of atmospheric air, a downward stream towards the interior of said film tube (3) being generated which pushes the product (P) with a flow greater than the flow of the injected gas.

6. Control method according to any of claims 1 to 5, wherein in the pressing step, the pressure is generated by a pressing device (6) comprising a first pressing member (6.1) facing a second pressing member (6.2) arranged downstream of the transversal actuation assembly (4), between which the film tube (3) is arranged when the film tube (3) is caused to move in the forward direction (A), said pressing members (6.1, 6.2) being configured to, in operation, physically contact the outside of the film tube (3).

7. Vertical packaging machine characterised in that it is adapted to implement the control method according to any of claims 1 to 6.

8. Vertical packaging machine comprising a transversal actuation assembly (4) configured to seal and transversal cut a film tube (3), characterised in that the machine (100) further comprises a tapping device (5) which is arranged downstream of the transversal actuation assembly (4) and which is configured to tap the film tube (3) from the outside and in an upward direction; a stream generator (7) configured to generate a downward gas stream that pushes the product (P) disposed inside the film tube (3) in a downward direction; and a pressing device (6) downstream of the transversal actuation assembly (4), for pressing the film tube (3) from the outside in a transverse direction to dislodge part of the gas disposed inside the film tube (3) downstream of the transversal actuation assembly (4).

9. Vertical packaging machine according to claim 8, wherein the tapping device (5) comprises a tapping member (5.0) that physically contacts the closed end of the film tube (3) downstream of the transversal actuation assembly (4) when actuated, or a nozzle to generate an air injection against the film tube (3).

10. Vertical packaging machine according to claim 9, wherein the tapping device (5) comprises an actuator (5.1) configured to cause a vibration of the tapping member (5.0) to intermittently tap the film tube (3).

11. Vertical packaging machine according to any of claims 8 to 10, wherein the stream generator (7) is configured to inject a gas in a downward direction towards the interior of the film tube (3), and to cause an atmospheric air suction due to a Venturi effect with said injection.

12. Vertical packaging machine according to any of claims 8 to 10, wherein the forming tube (1) is a coaxial tube formed by two concentric tubes between which a gap is defined, the stream generator (7) being configured to inject the gas into the film tube (3) through said gap.

13. Vertical packaging machine according to any of claims 8 to 12, wherein the pressing device (6) comprises a first pressing member (6.1) and a second pressing member (6.2) facing each other, arranged downstream of the transversal actuation assembly (4) and movable towards and away from each other.

14. Vertical packaging machine according to claim 13, wherein the first pressing member (6.1) is attached to a first tool (4.1) of the transversal actuation assembly (4) and the second pressing member (6.2) is attached to a second tool (4.2) of the transversal actuation assembly (4), wherein the first pressing member (6.1) and the first tool (4.1) of the transversal actuation assembly (4) facing the second pressing member (6.2) and the second tool (4.2) of the transversal actuation assembly (4) respectively, and the first and second pressing members (6.1, 6.2) being displaced in conjunction with the respective first and second tool (4.1, 4.2) of the transversal actuation assembly (4).

15. Vertical packaging machine according to any of claims 8 to 14, comprising a control unit (8) communicated with at least the tapping device (5), the stream generator (7) and the transversal actuation assembly (4), and / or with the pressing device (6), the control unit (8) being configured to coordinate the actuations between said devices (4, 5, 6, 7) to implement the compression stage of the method according to any one of claims 1 to 6.

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