CN1860063A - Cover film stretching device - Google Patents

Abstract

The invention relates to a packaging machine with which packaging cavities (3) are filled with a product to be packaged and are closed by a cover film (2). Said packaging cavities (3) are displaced in an intermittent manner along the packaging machine, and the cover film is stretched to its exact positioning on the packaging cavities. The invention also relates to a method for sealing a cover film on packaging cavities.

Description

Cover film stretching equipment

technical field

The present invention relates to a packaging machine, by means of which material to be packaged can be filled into a packaging slot and sealed with a covering film, wherein the packing slot is moved intermittently along the above-mentioned packaging machine, and the covering film is covered Stretch to position it precisely on the packing slot. Furthermore, the invention relates to a method for sealing a cover film on a packaging container.

Background technique

Currently packaged goods, especially food, are more and more frequently packaged in plastic packaging. These plastic packages consist of a so-called packaging channel, into which the material to be packaged is placed, and a cover film, which is sealed on the packaging channel and closes it by closing the packaging channel. Since these cover films are increasingly frequently printed with logos or product information, the exact positioning of the printed image of the cover film on the packaging slot must be ensured prior to sealing. In addition, in order to make the package have an attractive appearance, we hope that the packaging film is sealed to the packaging channel in a tensioned and stretched manner. This can be achieved by the printed image of the cover film being slightly smaller than the cross-section of the package slot to be sealed, with the result that the cover film must be stretched (orientated) prior to sealing.

Currently, this stretching is achieved by pulling the packaging channel forward, since the loosening of the cover film is briefly stopped before the packaging channel has finished pulling forward. However, this process does have the disadvantage that the printed image of the cover film is sometimes not positioned precisely enough on the packaging slot.

Contents of the invention

It is therefore the main object of the present invention to provide a packaging machine, and a method of sealing a cover film on a packaging slot, with which a printed image on the cover film can be positioned very accurately on the packaging slot , and sealed on the above-mentioned packing groove.

According to the invention, this object is achieved by a packaging machine by means of which the material to be packaged is filled into the packaging slot and sealed with a cover film which is stretched so that it fits precisely Positioned on the packing chute, and the packaging machine has a stretching device that is not based on the movement of the packing chute.

To a person skilled in the art, the very precise and smooth sealing of the printed image of the cover film on the packaging channel with the packaging machine according to the invention is very surprising and unexpected. The packaging machine according to the invention is easy and economical to manufacture and operate.

In a preferred embodiment of the invention, the stretching device has a clamping device, by which the cover film is held in such a way that it can be stretched. As a clamping device, any clamping device known to a person skilled in the art and by which fast, reversible and non-damaging cover film fastening can be achieved is conceivable. The expandable tubing mentioned here is just one example.

Furthermore, the stretching device preferably has a displacement device by means of which the clamping device can be displaced in such a way that the cover film is stretched to the desired length. The mobile device is preferably infinitely adjustable.

In a particularly preferred embodiment, the packaging machine according to the invention has a photocell, by means of which an imprint mark arranged in each case between two printed images can be detected.

In another preferred embodiment, the cover film is wound on a film roll which is then supported on a roll holder. The cover film is preferably tensioned by a tension roller.

The invention also relates to a method of sealing a cover film on a packaging slot which is intermittently moved along a packaging machine whereby the cover film is stretched so as to be precisely positioned on the pack slot and then sealed, The stretching of the cover film is thus accomplished without the aid of movement of the packaging groove.

The method according to the invention has the advantage of very precise positioning of the printed image on the cover film on the packaging slot. Implementation of the method is simple and economical.

Preferably, the cover film is fixed, sealed in a particularly preferred manner on at least one of the packaging slots, and the cover film is released from the film roll by intermittently pulling the packaging slot forward, and the forward movement of the packaging slot Once the pulling is complete, the cover film is held in place by the clamping device, stretched and then sealed.

In a particularly preferred embodiment, the actual position of the imprint marks can be detected during the unwinding of the cover film. The actual position thus determined is compared with the fixed point position, and based on this comparison, the amount of stretching (orientation) of the cover film can be determined. In order to avoid excessive stretching of the film, the maximum stretching amount is limited by the film formulation design.

Description of drawings

The present invention will be described below with reference to FIGS. 1 and 2 . This description is done by way of example only, and does not limit the whole concept of the invention.

FIG. 1 shows a cover film stretching device with a photocell and a stretching device with position data.

Figure 2 shows a cover film stretching device with displaceable photovoltaic elements.

Detailed ways

Figure 1 shows a packaging machine (only partly illustrated) according to the invention, in particular a stretching device and a sealing unit. The packaging tank 1 is conveyed along the packaging machine in the conveying direction indicated by the arrow 12 . Those of ordinary skill in the art will appreciate that many packaging slots may be arranged one behind the other on the plane of the paper. In the sealing chamber 14 the cover film 2 is sealed onto the packaging groove 1' which is now located in the sealing chamber. For this purpose, the lower sealing tool 15 can be moved up and down as indicated by the double arrow, so that the cover film 2 is sealed to the packaging slot 1' under the influence of temperature and pressure. Once the sealing operation is complete, the packaging slot continues to move forward. When the cover film is attached to the packing tank 1', the cover film 2 is unwound from the film roll 9 which is placed on the roll holder 10 as the pack advances. During the unclamping operation, the actual position of the imprint mark 8 located on the cover film and defining in each case a printed image can be determined, and the distance between the actual value and the defined fixed point value can be determined in a central control unit. Difference. This difference is then taken as the amount of stretched length that results from the difference between the actual value and the fixed point value. When the packaging slot has been pulled forward, the holding device 5 , in the present case an inflatable tube, is activated and can secure the cover film 2 . The cover film is then stretched by the movement device 6 by the calculated amount (orientation). For this purpose, the moving device moves in the opposite direction to the direction of travel of the cover film. In the present case, the mobile devices are driven by stepper motors or servo motors. The cover film is oriented (stretched) when it is fixed in the stretching direction 4 . Once the stretching of the cover film is complete, ie once the cover film is positioned exactly on the corresponding packaging slot, the sealing is done in the manner previously described. When the sealing operation is completed, the clamping means 5 are released and the moving means 6 return to their starting position. Movement of the mobile device may be represented by double arrows.

When processing a new cover film, the method used is changed as follows. First, the printed image of the upper film is placed as precisely as possible on the lower film and/or on the deep-drawn packaging groove in the lower film, then by a metrology method, the photocell 7 and the imprinted mark 8 of the reference are determined 'the distance between. This distance is the so-called fixed point value, which is communicated to a central control unit, eg via a control panel. The machine is then switched on and the cover film 2 is sealed onto the packaging slot 1'. With each pull forward of the lower film with the packing grooves, the covering film sealed to these packing grooves is released and the actual position of the imprinted mark is determined by means of the photocell 7 . The difference between this fixed-point position and the actual position is taken as the corresponding stretched length quantity. If the required stretch length exceeds the maximum stretch length allowed by the material, the stretch of the cover film should be limited to that maximum stretch length. In order to carry out the stretching operation, the upper film that has been pulled forward is fixed by the clamping device 5, and the moving device 6 moves in the opposite direction of the film traveling direction according to the defined stretching length. The determined set-point values are stored in the formulation of the film and/or product associated with the film in the machine.

A change of the cover film simply consists of inserting the film into the packaging machine and downloading the appropriate recipe and hence the set point values from a central control unit. After machine start-up, the system then automatically positions the printed image very precisely on the lower film and/or on the packaging slot in the lower film by means of the determination of the actual position of the imprint mark and subsequent stretching. The system also limits the maximum stretching length per stretching operation to prevent tearing of the cover film. This maximum stretch length is likewise included in the stored recipe.

FIG. 2 shows the cover film stretching device according to FIG. 1 , except that in the present case the photovoltaic element is supported displaceably, as indicated by the double arrow. Furthermore, the stretching device according to FIG. 2 does not have a displacement device with position data, but a displacement device with a position pattern. In other respects, the description of FIG. 1 applies. As mentioned above, the photovoltaic element can be moved in the direction in which the film is advanced and in the opposite direction. In the present case, by means of the manual displacement of the photocells, the fixed-point position of the imprint marks is adjusted to the various types of films. First, a photocell registers whether or not an imprinted mark travels over the photocell while the film is being pulled forward. When the forward pulling is complete, the stretching device 4 stretches the covering film 2 until the photocell 7 again detects the passing imprint mark. In the present case the stretching device 4 is driven by a cylinder (not shown) to which no position data may be supplied. When the imprint mark is detected, the stretching operation is terminated and the film is secured by sealing the film to the packaging slot. In the event that no imprint marks are detected, the full effective stroke of the cylinder is performed.

This embodiment of the invention is particularly suitable for the drive of stretching machines 4 without position data, eg cylinders.

All statements given regarding the device according to the invention also apply to the method according to the invention and vice versa.

List of reference signs:

1, 1' packing slot

2 cover film

3 packing slots

4 stretching equipment

5 clamping device

6 mobile device

7 Optoelectronic components

8, 8' imprint mark, imprint mark for reference

9 film roll

10 roller holder

11 Tension adjustment roller

12 Transmission direction

13 rollers

14 sealed chamber

15 Lower sealing tool

Claims (10)

1. Packaging machine, by means of which the material to be packaged can be filled into the packaging slot (3) and sealed with a cover film (2), wherein the packaging slot moves intermittently along the packaging machine, and the cover film (2) Stretched so that it is precisely positioned on the packing chute, characterized in that said packaging machine comprises a stretching device (4) which is not based on the movement of the packing chute. 2. Packaging machine according to claim 1, characterized in that the stretching device (4) has a clamping device (5) suitable for covering the film and a moving device (6). 3. Packaging machine according to any one of the preceding claims, characterized in that the machine has a photocell (7) for detecting the imprinted marking (8). 4. The packaging machine as claimed in claim 1, characterized in that the cover film is supported as a film roll (9) on a roll holder (10). 5. The packaging machine as claimed in claim 1, characterized in that the cover film (2) can be tensioned by means of a tension-adjusting roller (11). 6. A method of sealing a cover film (2) to a packaging slot (1) which is moved intermittently along a packaging machine and whereby the cover film (2) is stretched to make it precisely Positioned on the packing groove and then sealed, it is characterized in that the stretching of the cover film is achieved without the aid of the movement of the packing groove. 7. The method according to claim 6, characterized in that the cover film is fixed on at least one packing trough, the cover film (2) is released from a film roll (9) by the movement of the packing trough, and is clamped The device (5) is fixed, stretched and then sealed. 8. The method according to claim 6 or 7, characterized in that the actual position of the imprint mark (8) can be detected during the loosening of the cover film. 9. The method of claim 8, wherein the amount of stretching is determined based on the difference between the actual position and the fixed point position. 10. The method of claim 9, wherein the amount of stretching is limited based on film formulation.

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