WO1985004379A1

WO1985004379A1 - Process and installation for packaging objects

Info

Publication number: WO1985004379A1
Application number: PCT/EP1985/000136
Authority: WO
Inventors: Johann Natterer
Original assignee: Multivac Sepp Haggenmüller Kg
Priority date: 1984-03-30
Filing date: 1985-03-29
Publication date: 1985-10-10
Also published as: DE3411917A1; EP0175778A1; DE3411917C2; JPS61501624A

Abstract

Process for packaging objects wherein a cavity is formed from a sheet, the object to be packaged is introduced in the cavity, a cover is applied to the cavity, the pressure is lowered in the inner space of the cavity and in the outer space surrounding the cavity on its lower side and the cavity is closed with the cover by welding, respectively sealing. In order to avoid an expansion of the object to be packaged during the vacuum operation, a pressure difference is created when a first predetermined pressure is reached in the outer space, between the inner space pressure and that of the outer space so that the cavity is applied against the object to be packaged under the effect of the pressure difference. To this effect, there is provided a device (44, 45, 46) to produce a pressure difference between a higher chamber (11) and a lower chamber (17) of a vacuum and sealing station, as well as a control (37) which is intended to actuate the device (44, 45, 46) upon reaching the first predetermined pressure value in the lower chamber (17).

Description

Method and device for packaging objects

The invention relates to a method for packaging articles, in which a film trough is formed from a film, the object to be packaged is introduced into the film trough, the film trough is brought with a cover, the pressure inside the film trough and in which "the film trough" is lowered on its underside surrounding outer space and the film trough is sealed to the cover by welding or sealing, and the invention also relates to a device for carrying out this method.

Such a method, which, for example, in DE-O

26 41 160 is used in particular for the packaging of objects such as food, the shelf life of which can be extended by evacuation. at usually both the interior and the exterior space of the film trough is evacuated simultaneously until the end vacuum required for durability is reached. This final pressure is relatively high with an absolute pressure of approx. 5 to 10 mbar If products such as cheese, for example, are to be packed using this process that are finely divided or contain gases in bubbles, this evacuation can lead to expansion.

Likewise, an expansion in the evacuation of water-containing products such as sausages, particularly at elevated temperature of the products, can occur due to the evaporation of what at a decreasing pressure. In both cases, the E sion can lead to the destruction of the internal structure of the product or to bursting and tearing of the product.

τ§ From DE-OS 2404038 a method is known in which in a so-called chamber machine for packing poultry in a B tel in a first step the pressure au half of the bag is lowered to about 105 mbar and then the internal pressure to about 65 mbar is lowered. After the internal pressure has reached its low pressure, the external pressure is increased again in a last section, so that the pouch creates the product and is located between the product and the pouch

Air should be pushed out. When the internal pressure is reached, the above-described damage to the product due to the expansion cannot be avoided.

The object of the invention is to improve a method of the type described above and the associated device. In particular, the expansion of the bubbles or liquid in the product to be packaged is to be avoided.

This object is achieved by a method of the type described at the outset, which, according to the invention, is characterized in that, when a first predetermined pressure is reached, pressure difference between the pressure in the interior and the pressure in the exterior is generated, in such a way that the film trough under egg effect the pressure difference is pressed against the object. The device is characterized in that the control unit is designed in such a way that, when a predetermined pressure value in the lower chamber is reached, it controls the valves so that the pressure in the lower chamber rises and the evacuation in the upper chamber continues.

Further features of the invention are characterized in the subclaims g.

Further features and advantages of the invention will become apparent from the description of an embodiment of the invention in connection with the figures. The figures show:

1 shows a schematic side view of a packaging machine for the application of the invention; Fig. 2 is a schematic diagram of a first embodiment of an apparatus with a cut erfihdungsgemäßen ent _¬ long the line II-II in Fig. 1;

3 shows a schematic diagram of a second embodiment of a device according to the invention with a section along line II-II in FIG. 1; and

4 shows a diagram of the pressure curve according to the invention in the interior (dashed line) and in the exterior (solid line).

1 schematically shows a side view of a vacuum packaging machine 1 according to the invention with a molding station 2, a filling station 3 and an evacuation and sealing station 4. A material web 5 is drawn off from a supply roll 6 and successively through the shape. Station 2, the filling station 3 and the evacuation and sealing station 4 moves. In the forming station 2, troughs 7 for receiving objects are formed in the material web, into which the goods to be packed are introduced in the filling station 3. In the evacuation and sealing station 4, a second material web 8 is guided as a cover over the troughs and welded or sealed to form a closed package.

2 shows a section through a first embodiment of an evacuation and sealing station 4 according to the invention perpendicular to the feed direction of the material web 5 with the associated switching and control elements. The evacuating and sealing station 4 has an upper tool 9 and a lower tool 10. On the side facing the lower tool 10, the upper tool 9 has an upper chamber 11 which forms a recess and in which a heated sealing plate 12 with a heating element 13 is arranged. The Lower tool 10 is designed as a container open to upper tool 9, the side walls 14, 15, 16 of which enclose a lower chamber 17.

Between upper tool 9 and lower tool 10, a transport device 18, 19 is arranged on both sides, which material web 5 with the trough 7 and one in the trough

7 gripped introduced object 20 and moved into the evacuation and sealing station 4. To move the trough 7 into the evacuation and sealing station 4, the lower tool 10 can be moved up and down in the direction of the double arrow 21. The second material web is over the trough 7

8 brought as a cover that corresponds approximately to the width of the sealing plate 12 and is somewhat narrower than the upper chamber 11, so that there is a distance between the edges of the second material web 8 or the sealing plate 12 and the side walls of the upper tool 9 is formed.

The upper chamber 11 can be connected to a vacuum pump 24 via a first connecting line 22 and the lower chamber 17 via a second connecting line 23. Each of the connecting lines 22, 23 has a shut-off valve 25, 26 and in the areas 27, 28 of the connecting lines 22, 23 between the chambers 11, 17 and the shut-off valves 25, 26 one shut off by means of ventilation valves 29, 30 ¬ bare branch 31, 32 to the atmosphere. The valves 25, 26 and 29, 30 are each designed as solenoid valves and with outputs 33, 34; 35, 36 of a controller 37 connected. Further, in the region 27 and connected to the lower chamber 17 are excluded as a contact vacuum gauge _^ imaginary manometer 38, 39 are provided, whose outputs are connected to inputs 40, 41 of the controller are connected 37th The manometer 38 has at least one and the manometer 39 have at least two adjustable switching points which are set in a manner to be described later.

To produce a package, the trough 7 is filled with the goods or object 20 to be packed, the lower tool 1 is lowered and the trough 7 with the object 20 by means of the transport device 18, 19 under the upper tool 9 into that shown in FIG. 2 Position moved. The lower tool 10 then moves upwards and the trough 7 enters the lower chamber 17. Simultaneously with the trough 7, the second material web 8 is introduced into the evacuation and sealing station 1 and, together with the trough 7, delimits an interior space 42 which contains the object 20. The interior 42 communicates with the upper chamber 11 through the distances between the side walls of the upper tool 9 and the side edges of the second material web 8 or the sealing plate 12, while the outer space present between the lower tool 10 and the trough 7 43, which surrounds the trough 7 on its outside, is tightly separated from the upper chamber 11 and the interior 42 by the material web 5 or the trough 7.

The evacuation process now takes place, the pressure curve being shown schematically in FIG. 4. After the evacuation and sealing station 4 has closed, the control 37 closes the ventilation valves 29, 30 and opens the shut-off valves 25, 26 at the time t _Q. The vacuum chamber 24 connects the upper chambers 11 and 11 via the first connecting line 22 the interior 42 connected to it and the exterior 43 evacuated via the second connecting line 23. By connecting the first and second connecting lines, the pressure drop, as shown in FIG. 4, takes place to the same extent.

The first switching point of the manometer 39 is set to a pressure p, which is preferably of the order of 200 to 800 mbar and, according to a particularly preferred embodiment, is approximately 500 mbar. If the pressure in the interior 42 and in the exterior 43 reaches this first predetermined pressure value at the time point t ₁ , then the manometer 39 supplies a signal to the control 37 and the control 37 closes the shut-off valve 26 and opens the ventilation valve 30 Pressure increase in the outer space 43 up to a second predetermined pressure value p ₂ , to which the second switching point of the pressure gauge 39 is set and this emits a second signal to the controller 37, which then closes the ventilation valve 30 again, so that the pressure in the outer space remains about constant. In the meantime, the shut-off valve 25 remains open and the ventilation valve 29 is closed, so that the interior space 42 is continuously evacuated until a required final pressure of around 5 to 10 mbar is reached by the time t ₃ , to which the switching point of the Manometer 38 is set. When the corresponding signal from the manometer 38 is received, the control 37 closes the shut-off valve 25. The two material webs 5, 8 are then sealed to one another and the evacuation and sealing station 4 can be ventilated again.

By ventilating the outer space 43 from the time t., A differential pressure .DELTA.p arises between the inner space 42 and Exterior space 43, which presses the trough 7 towards the object 20 and both upwards against the second material web 8 or the sealing plate 12. As a result, air present between the material web 7 and product 20, product 20 and material web 8 and between 5 material web 5 and material web 8 is pressed out of the trough 7 into the upper chamber 11. Furthermore, the force exerted on the product by the differential pressure & p causes the object 20 to be supported or pressed together, thus preventing expansion of the object 20 or

10 is avoided. The differential pressure Δp is determined by

The choice of the first predetermined pressure value p .. and the second predetermined pressure value p ₂ is chosen such that a permissible expansion measure is not exceeded in accordance with the object 20 to be packaged. Finally,

15 that from the time t- the outer space 43 is no longer evacuated, the advantage is achieved that the evacuation to the required final vacuum can take place more quickly since only the inner space 42 and the upper chamber 11 have to be evacuated.

20 In order to avoid air pockets or air islands remaining between trough 7 and object 20 or object 20 and material web 8, the differential pressure at time t _{1 must be} at the first preselected pressure value p. if possible. are formed abruptly or the pressure rise speed when ventilating the outer space 43 is as high as possible, that is to say the time span Δt is chosen to be as small as possible. In practice, a value of .DELTA.t of the order of magnitude between 100 and 200 msec is considered to be favorable, so that the pressure increase between the first and the second preselected 30 pressure value takes place in a time which is less than a tenth the time required for the evacuation. For this purpose, the line cross-sections in the second connecting line 23 between the lower chamber and the ventilation valve 30 are chosen to be as large as possible and a shut-off valve is selected for the ventilation valve 30, which allows a quick opening, for example a flap or Slider valve.

3 shows a second embodiment of the invention, in which the required rapid increase in the pressure difference is practically easier to implement. For this purpose, the lower chamber 17 is connected to a buffer store 45 via a line 44 and a shut-off valve 46 which can be actuated by the control 37 is provided in line 44. The buffer store 45 is connected to a pressure source 48 via a further shut-off valve 47. Furthermore, a pressure gauge 49 is provided on the buffer store 45, which emits a signal to the controller 37 when a predetermined pressure in the buffer store 45 is reached.

In this embodiment, before each successive action on the trough 7 with the pressure difference, the pressure in the buffer store 45 is brought to a preselected value by opening the shut-off valve 47 until the preselected value is detected by the manometer 49 and sent to the Control 37 is reported. The pressure increase at time t. is then achieved not by opening the ventilation valve 30, but by opening the shut-off valve 46. Thereafter, the pressure in the outer space 43 rises almost suddenly due to the immediate pressure compensation between the buffer store 45 and the outer space 43. This increase in pressure and the second predetermined pressure value p _p is indicated by the choice of the size of the buffer memory 45 and the pressure in the buffer memory 45 affects. The pressure equalization can take place faster, the higher the pressure in the buffer store 45 is selected. Then, however, the buffer storage volume must also be selected to be the smaller in order to reach the second predetermined pressure value. The buffer storage volume is preferably selected to be smaller than the volume of the sub-chamber 17 and, according to a particularly preferred embodiment, approximately as large as the volume of the outer space 43, that is to say the sub-chamber volume minus the volume of the object or product 20. The preset initial pressure in the buffer store 45 before the pressure equalization can practically be chosen between about 0.5 and 3 bar absolute pressure, preferably between 1 and 1.5 bar. In order to achieve a possible rapid pressure equalization, the buffer store 45 is mounted as close as possible to the lower chamber 17 and is preferably flanged directly to the latter via the valve 46 or only separated from it by a short flexible line piece that allows the displacement of the lower tool 10.

It is thus also possible, by preselecting a correspondingly different outlet pressure in the buffer store 45, to use it for different sizes of the subchamber or the product volume. With a correspondingly larger volume of the outer space 43, the pressure in the buffer store 45 is chosen to be correspondingly higher and vice versa.

The process according to the invention thus has the advantage that the air contained in the package to be formed is pressed out or mechanically displaced and the product is supported in the trough in such a way that, depending on the selected one Differential pressure no or only a small expansion of the gas blow or can occur due to evaporation. The differential pressure can be formed either by lowering the pressure in the upper chamber or by increasing the pressure in the lower chamber. It is essential, however, that the differential pressure is formed fairly quickly and practically "suddenly" in the form of a "pressure jump". As a result, he is sufficient that the inclusion of air in the container, in particular between the product and the trough, which would occur with a slow formation of the differential pressure, for example in that the shut-off valve 26 would be shut off and not ventilated at the same time . As a result, however, a differential pressure of the interior of the trough relative to the upper chamber is briefly achieved, which presses the air still remaining in the trough into the upper chamber and accelerates the evacuation of the interior of the trough. Finally, only a smaller amount of air has to be evacuated, which on the other hand allows the use of smaller vacuum pumps with the corresponding saving in energy or a correspondingly faster evacuation. This is particularly important because, as a rule, the vacuum pump's performance represents the limiting factor in the performance of the packaging machine.

Claims

PATENT CLAIMS

1. Process for packaging objects, in which a film trough is formed from a film, the article to be packed is introduced into the film trough, a cover is placed over the film trough, the pressure in the interior of the film trough and in which the film trough is on it The outer space surrounding the underside is lowered and the film trough is closed with the cover by welding or sealing, characterized in that when a first predetermined pressure is reached, a pressure difference is generated between the pressure in the interior and the pressure in the exterior such that the film trough is pressed against the object under the influence of the pressure difference.

2. The method according to claim 1, characterized in that the pressure difference is generated by the fact that the pressure in the outer space is raised to a second predetermined pressure value.

3. The method according to claim 1 or 2, characterized in that the pressure difference is generated within about 100 to 200 msec.

4. The method according to any one of claims 1 to 3, characterized in that the raising of the pressure in the outside takes place faster than the lowering of the pressure in the inside and outside.

5. The method according to any one of claims X to 4, characterized in that the first predetermined pressure value is in the order of about 200 to 800 mbar.

6. The method according to claim 5, characterized in that the first predetermined pressure value is chosen between about 200 and 500 mbar.

"10 7. Method according to one of claims 2 to 6, characterized in that the second predetermined pressure value is in the order of about 150 to 250% of the first predetermined pressure value.

15 8. The method according to any one of claims 1 to 7, characterized in that during and / or after generating the differential pressure or increasing the pressure in the outer space, the interior of the film trough is further vacuumed to the desired final pressure.

20th

9. Vacuum packaging device for performing the method according to one of claims 1 to 8, with an evacuation and sealing station with an upper chamber, a lower chamber, an evacuation device.

25- with a first and a second connecting line for connecting the upper chamber or lower chamber with a vacuum pump or with a ventilation and a controller for controlling valves in the connecting lines,

30 characterized in that the control (37) is designed such that it controls the valves when a predetermined pressure value in the lower chamber (17) is reached so that the pressure rises in the lower chamber and the evacuation in the upper chamber is continued.

10. Vorrichtxing according to claim 9, characterized in that the lower chamber (17) via a connecting line (44) with a buffer memory (45) is connected.