WO1985003487A1

WO1985003487A1 - Packaging machine with sealing station

Info

Publication number: WO1985003487A1
Application number: PCT/EP1985/000044
Authority: WO
Inventors: Johann Natterer
Original assignee: Multivac Sepp Haggenmüller Kg
Priority date: 1984-02-08
Filing date: 1985-02-07
Publication date: 1985-08-15
Also published as: DE3404451A1; EP0186664A1; JPS61501143A

Abstract

Packaging machine (1) with an evacuation and sealing station (3) for welding what is called monofoils (6, 9) with a permanently heatable welding element. In order to prevent the monofoil from being destroyed by contact with the permanently heated welding element, there is provided a control (36) to create inside a chamber a differential pressure between the pressure on top of the upper foil and the pressure under the latter, so that the upper foil, during and after contacting with the welding element (13), remains stretched on the product and the lower foil. It is only after a cooling phase that the difference of pressure is supressed so that the package with the foil then restabilized may be removed and taken away.

Description

Packing machine with a sealing station

The invention relates to a packaging machine according to the preamble of claim 1.

With a packaging machine of this type, packs of composite films are normally sealed. The composite film has a carrier layer with a softening temperature and a sealing layer, the softening temperature of which is lower than that of the carrier layer. The sealing layer of the two foils to be sealed to one another are provided on the mutually facing surfaces. When sealing, the two sealing layers already adhere to one another at a temperature at which the carrier layers are still sufficiently stable to prevent them from being damaged. The sealing layers lying on the mutually facing inner sides of the foils cannot come into direct contact with the hot sealing or welding element.

A packaging machine of the type mentioned is known from DE-OS 21 02 890. In this known machine, the top film is first in contact with a pressure difference

^ V moved a sealing plate and then lowered together with this on the bottom film for sealing. Therefore, in this packaging machine the top film is in contact with the sealing or welding element for a long time before sealing. In the case in which a monofilm was used for the top film, this would cause the monofoil to melt at the contact surfaces with the sealing element, which can lead to undesired deformations of the top film and even to tearing or the formation of holes in the top film .

From DE-OS 27 58 808, a packaging machine is be¬ known, wherein ^"of the upper film to form a skin packaging by means of a differential pressure on the pressed product to be packaged and the lower film and sealed likewise by means of this differential pressure with DER lower film A separate, movable sealing element is therefore not provided in this device.

The object of the invention is to provide a packaging machine with a sealing station of the type described at the outset, which can also be used in particular for more complicated and different product packs, with which monofilms can also be sealed or welded.

This object is achieved by a packaging machine which is characterized by the features of the characterizing part of claim 1. This has the advantage that the monofilms even with such a packaging machine can be sealed or welded to one another in such a way that the monofilms are not damaged and a flawless sealing seam is created.

Further features and advantages of the invention result from the description of exemplary embodiments with reference to the figures. From the figures show:

1 shows a schematic side view of a packaging machine with the side wall omitted;

Fig. 2 is a section along the line II-II in Fig. 1;

3 shows a detail from FIG. 2 in a first operating state;

4 shows the detail in a second operating state;

5 shows the detail shown in FIG. 3 in a third operating state

and

6 shows a section corresponding to FIG. 4 according to a further embodiment of the invention.

As shown in Fig. 1, 1 ^• in a conventional manner, a forming station 2, and an evacuating and sealing station 3 to the packing machine, which are supported by a frame 4 each Maschinen¬. In a known manner, chains, not shown, are provided with clamping jaws, which transport a bottom film 6, which can be pulled off a supply roll 5, through the individual work stations and up to a schematically indicated cutting station. Between the molding station 2 and the evacuation and sealing station 3, the goods to be packaged are filled into the mold formed in the molding station 2. An upper film 9 is drawn off from a second supply roll 8 and is guided over the lower film in front of the evacuation and sealing station 3. As can best be seen from FIGS. 1 and 2, the evacuation and sealing station 3 has an upper part 10 and a lower part 11. The upper part forms an upper chamber 12 in its interior, in which a sealing or welding element 13, also referred to as a welding plate, is provided. This can be moved back and forth in a known manner into the retracted position shown in FIG. 2 or into the welding position shown in FIG. 5. Furthermore, the welding plate can be heated continuously to a predetermined temperature by means of heating elements 14. The upper chamber is connected to a vacuum pump 17 via a first discharge line 16 connected to a side channel 15. The upper part 10 can be moved in the direction of the double arrow 18 in the direction of the double arrow 18 relative to the lower part 11 upwards into the open position or downwards into the closed position shown in FIG. 2.

The lower part 11 forms in its interior a lower chamber 19 which receives the package to be sealed. It has an insert part 20 forming the wall of the lower chamber, which can be regulated to a preselectable temperature by means of elements 21 and a regulating device 41. A correspondingly shaped abutment 22 in the form of an elastic welding pad is provided at the points corresponding to the edge to be welded. This is in each case opposite the welding surfaces 23 of the welding plate 13 that interact with it during welding. The abutments 22 and the welding surfaces 23 interacting therewith have the shape of the weld seam to be formed. The lower part 11 has on the surface of its outer wall 24 a sealing rubber 25 which interacts with the outer wall 26 of the upper part 10 to seal the interior of the chamber from the environment.

On the side outer walls between abutments 22 and Sealing rubber 25 and, if desired, further locations of the depressions of the lower chamber 19 open out channels 27 which are connected to the vacuum pump 17 via a second discharge line 28. The lower part 11 can be moved downwards and upwards relative to the upper part 10 by means of a suitable drive in the direction of the double arrow 29 into the open position or upwards into the closed position shown in FIG. 2.

In the first derivative 16, a first shut-off valve 30 is provided, which is dependent on its valve state

^' connects the side channel 15 with the vacuum pump or disconnects from it. The first discharge line 16 can also be connected to the ambient air via a second shut-off valve 31 and to a compressed air source 33 via a third shut-off valve 32. In the second derivative 28, a fourth shut-off valve 34 is provided, which connects the channel 27 to the vacuum pump 17 or shuts it off. Furthermore, the second discharge line 28 can be connected to the ambient air via a fifth shut-off valve 35. The valves 30 to 35 are connected on the input side to outputs of a controller 36.

The controller is also connected via an output 37 to the drive (not shown) for upper part 10 and lower part 11. Furthermore, the controller 36 is connected via an outlet 38 to a valve 39, which connects an actuating element 40 for moving the welding plate 13 up and down with a compressed air source.

Furthermore, a control device 41 is provided, one input of which has a temperature sensor 42 which measures the temperature of the insert 20 and the second input of which has a the temperature of the welding plate 13 measuring temperature sensor 43 is connected. A third input of the control device 41 is connected to a time measuring device 43, which measures the duration of the contact between the welding plate 13 and the abutment 22 when welding the foils lying therebetween.

A first output 44 of the control device 41 is connected as an actuator to the input for the elements 21, and a second output 45 is connected as an actuator to the input of the heating elements 14.

As can be seen most clearly from FIG. 3, the bottom film 6 has longitudinal slots 47 on its sides, specifically at the points that come to lie over the lateral channels 27, which serve to connect the suction device to produce the pack interior 48 and the channel 27. The top film 9, however, is continuous and has no opening. The lateral edges of lower film 6 and upper film 9 lie between the sealing rubber 25 and the outer wall 26 and are clamped in this way between the upper part 10 and lower part 11.

The controller 36 is designed so that the workflow is controlled as follows:

In a first position, valves 30 to, 35 are closed and upper part 10 and lower part 11 are in the open position moved away from one another. Lower film 6 and upper film 9 with the trough formed and the product 46 located therein are moved between the chambers in such a way that the product comes to rest in the lower chamber 19 in the manner shown in FIG. 2. In the next step, the lower chamber and upper chamber are moved towards one another into the position shown in FIG. 2, so that lower film 6 and upper film 9 are clamped in at the side and the chamber interior is hermetically sealed against the outer has been largely completed. Now the shut-off valves 30 and 34 are opened, so that the interior of the lower chamber 19 and the packing interior 48 are evacuated via the channels 27 and the interior of the upper chamber 12 via the channel 15 in the manner shown in FIG. 3. In the next step the valve 30 is closed and at the same time the valve 32 is opened. This results in a pressure difference above the upper film 9 in the upper chamber 12 on the one hand to the space below the upper film, that is to say the interior of the pack and the inner space of the lower chamber on the other hand, which means that the upper film 9 closely adheres to the product 46 or applied to the bottom film, so that the top film is taut and not loosely and folded. The pressure difference is measured via a pressure difference meter 49, which uses a sensor 50 to measure the pressure in the upper chamber 12 and a sensor 51

Measures pressure in the subchamber or in the duct 27 connected to it. The output signal of the pressure difference meter is fed to the control device 36 via a corresponding line. As soon as a predetermined differential pressure is reached, which is selected so large that the upper film 9 is pressed firmly and tightly down onto the lower film and product, the valve 39 is opened via the outlet 38 and thus the actuating element 40 for the downward movement. Moving the welding plate 13 started. The welding plate 13 is moved downward from the position shown in FIG. 3 into the position shown in FIG. 4 in such a way that it applies light pressure to the bottom and top foils 6, 9 between the abutment 22 and the welding surface 23. Due to the heat transferred from the welding plate 13, welding takes place between the two foils. As best er¬ of FIG. 4 is arranged, is the top film 9 only at the bearing 22 facing the Wider¬ welding ^'ßflache 23, so that an uncon- trolled fusing and destruction of the upper film is avoided by uncontrolled contact of the upper film on side parts of the welding plate 13.

In the next step, the controller 36 controls the valve 39 and thus the actuating element 40 in such a way that the

Welding plate 13 is moved into the retracted position shown in FIGS. 5 and 2. As a result of the persistence of the pressure difference, it is achieved that even in the state shown in FIG. 5, the pack with the bottom film and top film remains firmly on the abutment and not with

Lifting the welding plate 13 is pulled up or torn open. This effect is reinforced to a certain extent by the fact that the welding plate has a corresponding coating such as a Teflon coating 52.

The negative pressure is maintained until the monofilm has cooled down, in particular also through contact with the welding pad, to such an extent that it has become load-bearing again. In the next step, the control 36 then controls the shut-off valves 32 and 34 into the closed position and the shut-off valves 31 and 35 into the open position, so that the interior of the evacuation and sealing station 3 is ventilated. As soon as the ventilation has taken place, the controller 36 controls the drive for the upper part 10 and lower part 11 via the output 37 in such a way that they are moved apart into the open position so that the pack can be moved out of the station.

The control device 41 is designed in such a way that it keeps the temperature of the insert part 20 and that of the welding plate 13 at a pre-settable constant temperature, where the presetting depends on the type of material of the film to be welded and the temperature of the welding plate 13. Furthermore, the control device 41 also regulates the temperature of the welding plate 13 to a preselected temperature.

The temperature of the abutment 22 and the insert 20 is of course sufficiently lower than that of the welding plate 13, so that the foils can be cooled.

In the exemplary embodiment described above, the welding takes place in an evacuation and sealing station

3, in which the packs are not only sealed but also evacuated. In another embodiment, only welding is carried out in station 3, but not evacuation. In this case, valve 3b remains open and valves 30, 31 and 34 are closed. The vacuum pump 17 can also be dispensed with entirely. It is only important that the first derivative 16 can be connected to the pressure source 33 in an adjustable manner and that the second derivative 28 leads to the environment. In this embodiment, the controller 36 is designed such that first the upper and lower parts 10, 11 are moved towards one another and thus the station 3 is closed. The valve 32 is then opened so that pressure is exerted on the two foils and these are pressed onto the welding pads in the manner shown in FIG. 2. Then, by actuating the valve 39, the welding plate 13 is moved downward into the position shown in FIG. 4, and the heat is transferred from the welding plate 13 to the foils and thus with the fusion shown in FIG. 4. In the next step, the pressure is maintained and the welding plate 13 is moved from the position shown in FIG 5 moved back position shown. As a result, the welded film remains in contact with the lower part 11, and the heat from the film is dissipated via the lower part until the film becomes self-supporting again. In a subsequent step, the valve 32 is closed and the valve 31 is opened to vent the chamber, so that the package with the then stable mold edges can be lifted off and moved on.

In the further embodiment of the invention shown in FIG. 6, parts corresponding to parts of the above-described embodiment are identified by the same reference numerals. In contrast to the embodiment already described, in this embodiment the welding plate 13 has an abutment 53 made of elastically deformable material on the inside of the welding surfaces 23. The abutment 53 has a surface 54 which protrudes downward beyond the plane of the welding surfaces 23 towards the insert 20 or the abutment 22, and is laterally displaced relative to the abutment 22 in such a way that it lies opposite an area 55 which abuts the abutment 22 inside.

The area 55 is also designed such that the abutment 22 protrudes beyond the area 55 by substantially the same amount as the abutment surface 54, the welding surface 23.

As a result of this additional abutment 53, the upper film is additionally pushed downward from the welding plate 13 when the welding plate 13 is lowered, which prevents the upper film from being placed on the welding plate 13 in an uncontrolled manner in the region adjacent to the welding surfaces 23. Due to the abutment 53, its surface 54 due to the low conductivity of the abutment material on an essential temperature is lower than the welding surfaces 23, the welding area is also limited too clearly on the inside and the risk of damage to the upper film is also avoided.

The monofilms used in the device described above are known per se. For example, it is a so-called RMHDPE (rubber modified high density polyethylene) film.

Claims

PATENT CLAIMS

1. Packaging machine with a sealing station for sealing or welding an upper film to a lower film, with an upper part and a lower part, which can be moved relative to one another into a closed or open position, with an abutment in one of the parts for one another foils to be welded and a permanently heatable sealing or welding element which can be moved to and from this in its working position for welding or sealing thereon, with a sealing or welding surface opposite the abutment, and a connecting line between the upper part and / or lower part and a Druck¬ air or vacuum source and a controller for controlling the connection of the upper part and / or lower part with the compressed air or vacuum source, characterized in that the controller (36) is designed so that before or at least simultaneously with the movement of the sealing or welding element (13) into the working position g, the upper film is subjected to a pressure difference, which presses the upper film away from the sealing or welding element in the direction of the product or lower film and is chosen so large that the upper film in the working position of the sealing or welding element (13) only touches the ^* welding surface (23) and that the pressure difference is maintained at least until the sealing or welding element (13) has moved away from its working position.

2. Packaging machine according to claim 1, characterized in that the controller (36) is connected to a differential pressure measuring device (49) which measures the pressure difference between the pressure in the upper part (12) and the pressure in the lower part.

3. Packaging machine according to claim 1, characterized in that in a known manner with a vacuum pump (17) connected first derivative. (16) in the upper part (10) and a second discharge line (28) connected to a vacuum pump (17) is provided in the lower part (11) in such a way that the control (36) is further designed such that for the purpose of sealing or When welding, first the interior of the station (3) is evacuated via both leads (16, 28), that the sealing or welding element (13) is moved into the working position, and that at least during the sealing process to achieve a pressure difference the line (16) of the part (10) having the sealing or welding element is shut off from the vacuum pump (17) and connected to external pressure or a compressed air source (33).

4. Packaging machine according to one of claims 1 to 3, characterized in that the pressure difference takes place before the sealing or welding element (13) is brought into the working position.