IT202000005182A1 - HEAT SEALING UNIT FOR PACKAGING MACHINES WITH VOLUMETRIC FLOW PARTIALIZING DEVICE - Google Patents

Description

Description of the patent for an invention entitled:

?UNIT? OF HEAT SEALING FOR PACKAGING MACHINES WITH

VOLUMETRIC FLOW PARTIALIZING DEVICE

Technical sector

The present invention relates to a unit? thermosealing device with continuous volumetric flow choking device for packaging machines, for example machines for packaging products in a container or tray by means of a heat-sealed film to the tray.

In particular, the shutter of the invention? conceived to be applied to packaging machines in which the film is made adherent under vacuum to the product to obtain the cos? said? skin effect? or for machines that perform heat sealing in a controlled atmosphere by introducing a gas into a unit? previously vacuum-packed.

State of the art

At present, packaging machines are known comprising a unit? of heat sealing divided into two chambers, one upper and one lower, which in the heat sealing phase overlap and are separated from the packaging film.

During the heat sealing process, one or both chambers can be subjected to a vacuum, more? pushed or not.

Depending on the type of packaging you want to carry out, you can? it may be necessary to obtain the same degree of vacuum in both chambers, for example before reintegration with gas in the case of heat sealing in a controlled atmosphere, or to have a prevailing vacuum in one of the two chambers, for example to make the film adhere to a hot wall of a chamber before the film cutting phase.

In different phases it will be able? a different alternation or balancing of the vacuum in the lower and upper chambers may be desirable.

Known systems therefore have many drawbacks. do not allow to vary the balance during the different stages of the packaging process, thus limiting? the possible operations that can be performed in the unit? heat sealing.

Purpose of the invention

The present invention therefore intends to overcome the drawbacks of the already existing solutions. notes and propose a unit? heat sealing system equipped with a flow choke in packaging machines equipped with an upper chamber and a lower packaging chamber, which allows a continuous, rapid and flexible management of the volumetric flow entering and leaving the lower and upper chamber.

Summary of the invention

For these purposes, yes? received by making a volumetric flow restrictor for packaging machines according to at least one of the attached claims.

A first advantage consists in the fact that it is possible to obtain an effective management and balancing of the vacuum in the unit? heat sealing and continuous adjustment of the pressure difference between the two chambers based on the vacuum reached.

An additional advantage is that? Is it possible to perform different work phases in the same unit without structural changes? of heat sealing that require different vacuum conditions, for example thanks to the regulation that can be implemented in the unit? of the invention? Is it possible to foresee an automatic adjustment of the flow throttle that avoids manual changes to be made on the vacuum management system when switching from packaging to mode? controlled atmosphere to the packaging with a? skin? effect.

List of drawings

These and further advantages will be better understood by every person skilled in the art from the following description and the attached drawings, given as a non-limiting example, in which:

- fig.1A schematically shows a unit? heat sealing in a conventional packaging machine;

- fig. 1 shows a throttle device according to the invention applied to a unit? heat sealing of a packaging machine;

- fig.2a-2c show a detail of three different configurations of the shutter of fig.1;

Figure 3 shows in greater detail a shutter according to the invention.

Detailed description

With reference to the attached drawings, a unit is described. of heat sealing U according to the invention, intended for use in packaging machines for products P contained in a tray V, by heat sealing a film f to the peripheral edge 5 of the tray or container.

The unit? described comprises a lower bell 1 and an upper bell 2 which can be superimposed and sealed so as to define a heat-sealing chamber 3 inside which the heat-sealing process of the film to the tray takes place, for example by means of heat-sealing bars 4a, 4b.

The lower and upper bell are reciprocally movable between a non-operative remote position, in which the film f pu? be passed between the two bells, and a sealed operating position in which the bells are separated by the film (f) which defines cos? two distinct regions communicating with a vacuum source, for example a vacuum pump, by means of respective suction points 6a, 6b which, in the example described, connect the vacuum source 7 to the lower bell 1 and upper bell 2.

According to the invention, and with particular reference to figure 1, the unit? U comprises a vacuum choke device 8) interposed between the vacuum source 7 and the suction points 6a, 6b of the lower and upper bells 1, 2. The choke 8? equipped with adjustment means 9 to choke the vacuum created by said source between the lower and upper bells and determine so? the best operating conditions depending on the packaging process to be implemented.

In the example of embodiment illustrated, the adjustment means 9 comprise a three-way valve connected to the source 7 and to the lower and upper bells, which can be operated by means of an actuator 10 between a position of maximum partialization towards the lower bell and a position of maximum partialization towards the upper bell and capable of partializing with continuity? the volumetric flow between the lower and upper bells.

Preferably, the three-way valve? shaped with a first hollow outer sleeve 11 provided with two openings 12, 13 communicating respectively with the suction points 6a, 6b and inside which a second inner sleeve 14 runs tightly between two extreme positions, integral with the movement of the control stem 19 of a linear actuator 10.

The inner sleeve 14 has a cavity? 34 which communicates at one end? 32 with the vacuum source 7 and? provided with openings 15, 16 which in use face the openings 12, 13 of the outer sleeve 11 in such a way as to define each one an intake opening 17, 18 of variable dimensions between a maximum dimension and a minimum or zero dimension, and vice versa the other in correspondence with the position assumed by the inner sleeve 14 in its sliding between the extreme positions.

In Figures 2a-2c? shown as an example the shutter with the internal sleeve 14 in the extreme right position with suction completely towards the upper hood (fig.2a), in the extreme left position with suction completely towards the lower hood (fig.2b), and in central position (fig.2c) with 50% partialized intake or intake towards the two bells.

With reference to Figure 3,? illustrated a three-way capacity control valve in which the openings 12, 13 of the outer sleeve 11 are constituted by holes inclined with respect to the axis? a? of the sleeve and communicate with the suction points 6a, 6b by means of blocks 38, 35 in turn provided with aligned holes 39, 40 and of the same diameter as the openings 12, 13, tightly fixed to the cylinder 11 by means of gaskets 33. at the end, the cylinder 11 further provides a block 37 fixed to the cylinder 11 by means of a head gasket 36.

In this embodiment, the openings 1516 of the inner sleeve 14 are also obtained by drilling of the same diameter and inclination of the openings 12, 13 and the sleeve 14? equipped with an end attack? 40 for connection to actuator 10.

Preferably, the unit? U further comprises at least one pressure sensor 21, 22 applied to detect the internal pressure in at least one of said lower and upper bells 1, 2.

A filter 23 and a safety valve 24 can also be interposed in the line between the throttling valve 8 and the vacuum source 7.

The unit? of the invention can? be applied to different types of packaging processes.

As an example, I can? be it packaging in a controlled atmosphere or with a? skin? effect. that is, which determines a substantial adhesion of the film on the product.

In the first case, the heat sealing process involves a phase of creation of the same degree of vacuum in both bells and subsequently the reintegration with the introduction of gas (for example O2 or CO2) in at least one of said lower and upper bells of chamber 3 through at least one make-up valve 20 communicating with a suction point 6a and / or 6b.

In particular, two valves 20, 30 may be provided respectively for the reintegration of air between the upper chamber and the shutter and for the reintegration of gas in the lower chamber.

After the reintegration or the creation of a controlled atmosphere in the chamber 3, the thermosealing and the cutting of the film at the edges of the tray are then carried out.

In the second case, represented as an example in fig.1a, the unit? heat sealing? provided inside the lower and upper bells 1, 2 respectively, with a mold or lower tank 25 with a housing 26 for the tray and with an upper heat-sealing plate 27 which can be superimposed on the mold 25.

The heat-sealing means comprise first and second heat-sealing bars 4a, 4b associated respectively with the mold and the plate and which in operation can be mutually approached in correspondence with the perimeter edge of tray V.

In different examples of construction and type of film used (flat or mono folded), the bars 4a, 4b can be arranged in a? L? or a? C? at different perimeter edges so as to be able to completely seal the open edges of the film in correspondence with the tray.

In order to obtain the? Skin? Effect, the plate 26 can? be provided with a heated wall 29 equipped with holes 30 communicating with the upper hood 2 useful in combination with the pressure in the lower chamber which pushes the film into contact with the upper plate to suck and hold the film (f) in contact with the wall 29 in the presence of prevailing vacuum in the upper hood 2 until the film softens and then, in the reintegration phase, for the reintroduction of gas into the upper chamber.

After the heating of the film, the process involves a reintegration phase with the introduction of air into the upper chamber through the holes 30 (possibly part of the air can also be introduced into the lower chamber) and then the heat sealing phase, for example by means of bars. welding and cutting, for example by means of perimeter blades 45, of a per se known type, schematized in fig.1a. Still with reference to the machine of Fig. 1A, in a possible packaging process the following steps can be provided, given by way of example

1) Departure (shutter configured to divide between the two chambers at 50% -50%.

This initial balancing is intended to prevent the film from being? Sucked in? / pushed too violently against the sealing plate and prevent the film from being damaged;

2) Phase of reaching vacuum set (99% empty) In this phase, the shutter operates in such a way that in the upper chamber there is always a little? pi? vacuum to keep the film in contact with the heating plate 29.

3) Maintenance phase, for a certain time the pump maintains the vacuum set to allow the film to heat up further;

4) As soon as the film has the desired temperature, the shutter can? move and create slightly more? vacuum in the lower chamber where the product is located, allowing the film to gently rest on the product;

5) When the shutter is in the desired phase, the air is replenished.

In a further example of operation, the following configurations of the throttle can be implemented, which will vary according to the vacuum level reached for reaching and maintaining a difference of 1% of the vacuum with head in the upper chamber.

0% vacuum level

Shutter opening: (upper 55% -45% lower)

Vacuum Level 50%

Shutter opening: (upper 60% -40% lower)

Vacuum Level 90%

Shutter opening: (upper 65% -35% lower)

Vacuum Level 95%

Shutter opening: (upper 75% -25% lower)

Vacuum level 98%

Partializer opening: (upper 90% -10% lower).

The invention achieves important advantages due to the fact that it is possible to obtain an effective management and balancing of the vacuum in the unit. heat sealing and continuous adjustment of the pressure difference between the two chambers based on the vacuum reached.

In particular, in the initial phase of aspiration of the air present in the tank (lower and upper chamber), the shutter of the invention allows the control of the outflow from the lower and upper chamber ensuring a very rapid and flexible management of the desired vacuum degree. , absolute and relative of each room.

Furthermore, subsequently, when an air or gas re-introduction or reintegration phase is carried out, the throttle allows independent control of the flow entering the lower and upper chamber so as to create a precisely controlled overpressure in the desired chamber so that the overpressure control must be precise and vary according to the desired packaging. For example, in the particular case of a? Skin? Effect car? to get a good effect? the overpressure must be high, but at the same time? useful to be able to reduce it in the case of? skin? of food in? weak? such as carton or PS foam. On the contrary, in the case of controlled atmosphere packaging? It is desirable to avoid an excessive pressure difference to prevent the film from moving and being marked by the sealing plate. Again, an overpressure compared to the atmospheric pressure in the package? useful to counter the collapse of the package due to the absorption of CO2 in food (especially beef).

An additional advantage is that? Is it possible to foresee an automatic adjustment of the flow throttle that avoids manual changes to be made on the vacuum management system when switching from packaging to mode? controlled atmosphere to packaging with a? skin? effect using the same unit? heat sealing.

These application examples are given as an example but we mean that the unit? of the invention will be able? it can also be used in different packaging processes that require the creation of vacuum conditions in two bells of a sealing chamber of a film to a tray.

The present found? been described according to preferred embodiments but equivalent variants can be conceived without departing from the scope of protection granted.

Claims (11)

CLAIMS 1. Unit? (U) for packaging machines for products (P) contained in a tray (V), comprising a lower bell (1), an upper bell (2) that can be superimposed in a fluid-tight manner on the lower bell to define a heat-sealing chamber (3), the lower and upper hood being reciprocally movable between a non-operative remote position and a sealed superimposed operating position in which the lower hood and the upper hood are separated by the film (f), means (4a, 4b) for heat sealing a film (f) to a peripheral edge (5) of a tray (V) in correspondence with said operating position of the bells (1, 2), at least one vacuum source (7) suction points (6a, 6b) connected to the vacuum source (7) to create vacuum inside at least said lower hood and / or said upper hood characterized in that it comprises a flow choke device (8) interposed between said vacuum source (7) and first and second suction points (6a, 6b) respectively of said lower and upper bells (1, 2) and equipped with means adjustment (9) to independently choke the inlet and outlet flows in and from the lower and upper bells on the basis of the vacuum level created by said source. 2. Unit? according to claim 1, wherein said regulating means (9) chokes said flows continuously. 3. Unit? according to claim 1 or 2, wherein said regulating means (9) comprise a three-way valve connected to the source (7) and to the lower and upper bells (1, 2) which can be operated by means of an actuator (10) between a maximum partialization towards the lower bell and a maximum partialization position towards the upper bell. 4. Unit? according to claim 3, wherein said three-way valve comprises a first external hollow sleeve (11) provided with at least two openings (12, 13) communicating respectively with the suction points (6a, 6b), inside which it slides tightly between two extreme positions a second inner sleeve (14) communicating with the vacuum source (7) and provided with openings (15, 16) facing said openings (12, 13) of the outer sleeve (11) so as to define each a suction port (17, 18) of variable dimensions between a maximum dimension and a minimum or zero dimension, and vice versa the other, in correspondence with the sliding of the inner sleeve (14) between said extreme positions. 5. Unit? according to claim 4, wherein said inner sleeve (14)? integral with the movement of the control stem (19) of a linear actuator (10). 6. Unit? according to one of the preceding claims, comprising at least one make-up valve (20, 30) communicating with a suction point (6a, 6b) for introducing air or gas into at least one of said lower and / or upper bells. 7. Unit? one of the preceding claims, comprising at least one pressure sensor (21, 22) applied to detect the internal pressure in at least one of said lower and upper bells. 8. Unit? according to one of the preceding claims, comprising a filter (23) interposed between the source (7) and the shutter (8). 9. Unit? according to one of the preceding claims, comprising a safety valve (24) interposed between the source (7) and the shutter (8). 10. Unit? according to one of the preceding claims, comprising at least one lower mold (25) with a housing (26) of at least one tray (V) and an upper heat-sealing plate (27) which can be superimposed on the mold (25), said mold (25) and said plate (26) being arranged inside respectively the lower and upper bells (1, 2) at least in said operative position, wherein said heat-sealing means comprise first and second heat-sealing bars (4a, 4b) associated respectively with the mold (25) and plate (26) and mutually approachable at at least a portion of the perimeter edge of the tray (V). 11. Unit? according to claim 10, wherein said plate (26)? provided with a heated wall (29) equipped with suction holes (30) communicating with the upper hood (2) to retain the film (f) in contact with the wall (29) in the presence of vacuum in the upper hood (2). .