EP1339609B1 - Method and device for positioning a web of film of a packaging device - Google Patents

Abstract

The invention relates to a method for positioning webs of film of a packaging device, according to which goods are introduced into a first web of film in troughs, a second web of film is withdrawn from a supply of web against the resistance of a brake and is placed on the first web of film and interlinked with the same, the advance of the second web downstream of the supply of web being detected by a first optical recognition means. In order to exactly position the two films one on the other, a second recognition means is provided that detects any dimensional errors, thereby changing the position of the first recognition means relative to the direction of conveyance of the second web of film.

Description

The invention relates to a method for positioning of Film webs of a packaging device, in which an in Feed direction moved first sheet goods in troughs this first sheet of film are inserted, then one of a Rail stock against the resistance of a brake subtracted second Film web placed on the first film web and with this is connected, wherein the feed of the second film web detected behind the track stock by a detection means and by varying the braking force of the brake as a function of Signal of the detection means is set, so that respectively a repeat as a defined region of the second film web the troughs of the first film web comes to rest. Further concerns the invention a packaging device for carrying out this procedure.

Such a method or such a packaging device is generally known from US 3427778 and from US 3979877 and from DE 4041547. This is the first film web provided with the hollows, inserted in the goods to be packed become. Subsequently, the second film web on this first placed with the goods stocked film web and either in vacuum technology or even with trapped air, for example in a sealing station welded with this. Below are then the individual troughs with the surrounding area of the film separated from each other and so produced individual product packaging. This packaging technique is commonly used for food used, but is also common for other goods. to Labeling of the packaging will usually be at least the second Printed film web, this often happens completely Thus, for example, the packaged goods protected from UV light can be. The imprint is according to the packaging length subdivided into repeats, so that over each trough one each Rapport comes to rest.

For optical reasons and for an air-safe welding ensure the upper second film web is preferred under tension, so that in the later packaging no Wrinkles. For this purpose, against the restraining force of an adjustable Brake the second sheet of film withdrawn from a supply, for example, may be formed by a roll. About guides is the so under tension second Film web placed on the first film web and then welded, wherein by adjusting the braking force, the position and stretching the flexible film web can be adjusted. In practice, for example, the imprint is carried out in this way be that the desired picture only after a certain bias of the second film web results.

The position of the individual reports is via a detection means made, via a scheme, the braking force can be adjusted so that the feed speed the second film web adapted to that of the first film web can be.

Although this is for the general regulation of the packaging machines is sufficient, it has been proven that often low Position deviations are possible, so that the rapports not one hundred percent exactly above the hollows come to rest. Especially for packaging that prints to the edge to be, this proves to be disadvantageous because, firstly a worse quality impression of the so packaged goods arises and secondly, if the position deviation even Required information no longer about the actual packaging come to rest, but in the context of the subsequent cutting process be cut away, the goods no longer marketable is. For example, information such as the best-before date may be used of a food or weight indication this way under no circumstances from the field of later Packaging fall out.

The object of the invention is therefore to provide a method for positioning the film web and a packaging device for exact and easy positioning of the repeats of the second Create film web over the troughs of the first film web.

This object is achieved according to the invention in that over a second detection means the exact position of the repeat is detected relative to the first film web and dimensional deviations the position of the first detection means relative is changed to the conveying direction of the second film web.

Due to the inventive design of the packaging process It is now possible via the second detection means to make an exact position definition. Is found here that the position deviates from the target position, so is about changing the position of the first detection means a control intervention made.

Due to the inventive design is achieved that of the control of the actual state by the second detection means the position of the first detection means relative to Conveying direction of the second film web is changed. This This leads to the fact that due to the control loop, which from the first detection means and the braking force, this one Control loop is influenced accordingly. For example, does it that the second detection means determines that the repeat is located slightly in front of the required position, So if something comes to lie in front of the hollows, the front would be Area of a possibly applied printed image cut off become. In this case, the position of the first recognition means becomes back-oriented, that is, against the direction of conveyance the second film web changed, making the first detection means register the report accordingly earlier and then the Brake correspondingly stronger pressed to a lesser extent Deduction of the second film web the position of the second film web Correct accordingly over the first film web.

The proposed method is particularly applicable to packaging devices, which run fully automatically. The However, the method is equally suitable, for example in be used in other manufacturing processes, in which it is particularly important to two slides over each other position. Usually, the first film web, which picking up the goods to be packaged, referred to as sub-rail, the second film web which closes the troughs becomes commonly referred to as upper web.

The inventive proposal ensures that a self-adjusting system is created. On the arrangement the upper course with respect to the lower course when setting up the Machine is no longer highly accurate, because the two detection means in cooperation with the graduated intervention in the respective control circuit and the brake and the inherent elasticity the foil the appropriate positioning of the Reach the upper orbit on the lower runway. The process is running fully automatic.

The proposal according to the invention is not only a Format change speeds up the necessary adjustments are reduced by the proposal according to the invention, but It also gives a higher stability during operation It has been found that the tension of a web supply withdrawn film web during processing is not always is equal to. The film becomes after the production for example Turned on a winding, where also the web something is stretched or wound under tension. This dimension is not always the same along the conveying direction, as a result, a certain offset of the Rapportes occurs, even if the rapport at the beginning exactly on the trough was aligned. This effect is also due to the inventive proposal automatically compensated. In the result the invention achieves a lower manual or Personnel positioning effort when changing a film web and a higher stability, that is, consistent Quality of the packaging.

The film web can be actuated due to its inherent elasticity the brake or release the brake in a certain Scope be offset so that with a corresponding signal of the first detection means, the controller a control intervention can make. Detects the second optical detection means a positional deviation of the repeat of the second film web relative to the trough in the first film web, then becomes the first detection means erwas, so that the brake either (something) to be solved or early attracted more. When releasing the brakes, the elasticity of the film is make sure that the rapport is pulled forward a bit.

On the other hand, it is possible that the second film web the Feed the first sheet trailing, so the rapport located slightly behind the position of the trough. In this Case, the brake can be solved, with constant pull-off force will be the feed rate of the second film strip increase, and thus the caster can be caught up again become.

It is possible, a correction or accurate positioning to reach the film web either via their own elasticity, which, of course, only claims tear resistance can be, or that feed or brake for the Film web can be controlled so that - without additional utilization the elasticity - the relative position of the upper foil web on the film web with the hollows is changed. Also This makes it possible to determine the relative position of the first Recognition means in the conveying direction of the second film web change.

To carry out the said method, the detection means The position of the report can determine what Conveniently done by so-called tax stamps, by the detection means of the remaining area of the film web can be distinguished. Such control means can for example, (optical) markings on the film web, but it may also be possible that on the basis of certain imprints the position of the repeat is identified. Also one Detecting the position, especially the position of the lower one Foil tape over edges or other significant parts of the Slides is possible. Alternatively to the use of optical, ie visible tax stamps, it is also possible that not visible marks, for example ultraviolet reflecting Tax stamps and so on. conveniently, is of course the training of the detection means of the tax stamp customized. But it is also possible, instead of detection means other sensors such as Hall sensors or to use different-acting sensors, the corresponding to Means are sensitive as control marks on the film web.

The optical detection means may be simple Photocells act that respond to a specific signal strength. Here, the necessary light that the photocell switches, either as reflected or transmitted light fall on the cell. With a transparent packaging can For example, a light beam, which also from a low-performance Laser beam can exist, through the packaging, the means to shine through the first and the second film web, so that when passing a dog tag this Beam is interrupted for a defined time. At this Design it is possible in the first as well as in the second film web to provide a dog tag.

In order to be able to distinguish which of the tax stamps which film web belongs, the tax stamps can be different Have expansions, so that a signal different Length of the photocell will be generated. By the inventive design of the method, it is now possible not only the feed rate of the second foil strip to detect via the first optical detection means and to settle, but it can be about the second Detecting means also the relative position of the first foil strip be determined relative to the second film strip.

In a preferred embodiment of the invention is provided that the second detection means in turn consists of several at a distance (in the conveying direction) arranged sensors consists. Such an arrangement is favorable, for example, when the Conveying speed is not known exactly and by the second sensor a speed or time measurement and thus an offset measurement is possible. Usually, otherwise the offset of the first detection means determined via the known conveying speed, the Recognition means provides only a time value on this Offset.

Instead of the photocells, other optical detection means, such as a line scan camera or another Camera, to be used. Due to the increasingly faster image processing Can via a camera at a defined position the second film strip are taken from above and, if so the printing of the second foil tape allows this, also the Determines the position of the underlying first foil strip become. On the other hand, there is a shine through the second foil strip not possible, by using a second camera Also, the bottom lying first foil strip can be determined exactly. A subsequent image analysis then allows an accurate Determining the position of the two bands.

The second foil tape is usually provided with information about the goods to be packed and printed with promotional motifs be. However, it may also be possible that this second Foil tape is not printed and either from a transparent or a non-transparent, especially colored Plastic exists. In these cases, the tax stamp through additional tools such as dashes or other specifically arranged optical defects implemented become. Thus, for example, the rapport through a local Change the reflection properties to be marked. A Such changes can be made, for example, by matting one otherwise achieve a shiny surface. Also, for example possible, an ultraviolet radiation activatable Provide reflector layer as a tax stamp.

In a further preferred embodiment of the packaging device will the welding device after alignment the first film web relative to the second film web, the trough sealed by connecting the two film webs (= sealing station), triggered by the second optical detection means. This means that the welding process is only triggered when the second optical detection means of the controller signals that the orientation of the two film webs relative to each other corresponds to the desired state. In this way It automatically avoids inaccuracies in the packaging occur.

In order to adjust the packaging device to a To achieve a plurality of possible dimensions, the position is preferred the first and the second detection means in the feed direction adjustable. By the invention further development is achieved that in a simple way the device other Rapport- or packaging tray lengths are converted can. Conveniently, this adjustability is electronic monitored and controlled mechanically or electromechanically. Also the position in the direction perpendicular to the feed motion can be adjustable so that different widths of the Film webs can be processed.

According to the invention it is proposed that the second detection means is arranged either before or after the sealing station. The advantage of an arrangement after the sealing station is that here upper and lower web are already welded together so sure of the actual state, namely the state of the finished Packaging, is verifiable. The disadvantage here is that the Packaging is already closed and possibly as a committee to treat. Conversely, the use of the second detection means before the sealing station still one certain correction possibility, so that the films in the sealing station correctly connected.

It has already been pointed out the advantages that time film web, so the top sheet, under tensile stress with to connect the first film web. This avoids that Wrinkles or waves arise.

In a preferred embodiment of the invention, it is provided that is the measure of the position correction of the first detection means the dimensional deviation caused by the second detection means is determined, corresponds substantially. It can in this case an interval of about 70% to 130% of the known dimensional deviation given in particular by the Elasitzität of the film and also by the way of Control loop depends. Alternatively, it is provided that the Measure the position correction of the first detection means by the dimensional deviation is limited as the maximum value. It is included also possible that in significantly smaller correction steps in Regarding the deviation is corrected to gradually to touch the right orientation.

It is favorable that the positioning method is periodic is performed, wherein the period is longer than that Processing time that passes while a rapport of the first conveyed to the second detecting means. Becomes in a control cycle the control cycle is chosen shorter than itself a change made in the system has spread first, this results in fluctuations or beats in the System and the desired result is not achieved. Of the Therefore, the control loop must have a certain "inertia", which in the present case by a distance of the two detection means on the one hand and through the average conveying speed is determined. The inventive development is provided that not too early a change again from the controller is placed before the first correction is checked is. Under certain circumstances, this length can also be up extend to the distance of the second detection means of the brake, because there are new properties in this area.

Other features and advantages of the invention will become apparent the dependent claims and from the following description a preferred embodiment with reference to the drawing, showing a packaging machine according to the invention.

In the single figure is a packaging device according to the invention, in particular for carrying out the inventive Packing procedure stylized illustrated. For the Packing of goods will be a first film web (sub-web) 1 in Moving feed direction, wherein in this first film web. 1 Trays 8 are introduced, in which the goods are stored. To seal these wells 8 is from a web supply 3 a second film web (upper web) 2 deducted by deflection rollers (not shown here) on the first film web. 1 is hung up and then by a here also not illustrated seal in a sealing station with the first Film web 1 is welded.

On the second film web 2 are usually imprints be arranged, which are divided into individual reports 7, so such a repeat over each of the troughs 8 to lie comes. These reports usually contain a print with which the goods advertised / described and other necessary information be made to the contents of the packaging container. Off (in particular For quality reasons, it is desirable that the repeat 7 is located just above the troughs 8 so that during the subsequent cutting process not part of the Rapportes 7 is cut off. In the worst case would thereby even legally prescribed information cut out so that the goods would no longer be marketable.

The illustrated packaging machine is a simple embodiment, usually several repeat reports 7 and troughs 8 be arranged in a row next to each other, so that in For example, you can have four packages at the same time can be produced.

The second film web 2 is by a pulling device of the Web supply 3 unrolled, where they by a brake 6 to tension is held. This voltage causes the over the Mulde 8 arranged film is under tension and so on smooth wrinkle-free surface is created during subsequent packaging. To the position of the repeat 7 relative to the position of Being able to determine well 8 is a first (optical) recognition means 4 provided that when unwinding the second Film web 2 from the web supply 3 control marks on the second Film web recognizes and a control of the packaging machine the position of these tax stamps reports.

Due to the inherent elasticity of the film, however, it can happen that despite this position control the reports 7 not exactly come to rest over the hollows 8. For this purpose, the inventive Packaging device, a second (optical) detection means 5 on, before or after welding the first film web 1 with the second film web 2 the position of the report once again based on tax stamps.

In the drawing, it is shown that the first detection means 4 is held movably on a guide 10. The mobility is indicated by the double arrow 11, wherein this mobility parallel to the conveying direction of the upper web. 2 is. In the embodiment shown here moves the recognition means 4 vertically, but the same arrangement also possible in horizontal orientation or at an angle.

Is now from the second detection means 5 is an offset of the Upper web 2 with respect to the sub-web 1 found (this takes place normally in the controller 9, which via the line 11 with the second detection means 5 is connected), is of the Control 9 off via the line 12, the drive of the first Detection means 4 activated such that the detection means 4 along the double arrow 11 in the corresponding from the controller predetermined direction is offset. This will result itself, that of the first detection means 4, the tax stamp on the upper orbit 2 is detected sooner or later what about the Line 13 of the controller 9 is communicated. Depending on this Information is the controller 9 via the line 14 regulating act on the brake 6 and close or open. As a result, exactly the repeat 7 can be positioned. There already a rough presetting by the first recognition means 4 is done, the required length compensation kept within limits, so that the imprinted on the repeat 7 Image visually only insignificantly by the stretching of the Slide is changed. By the inventively proposed In principle, however, a method is also a self-adjustment possible.

Tax stamps can be introduced auxiliary lines, optical defects, which are deliberately introduced into the film, or also the repeat itself or edges of the slides. In the illustrated Case, the optical detection means 4, 5 include a Light source and a photocell, which reflected the film Light of the light source absorbs and so passing the Detects tax stamps. Alternatively, a transmitted light measurement could also be used take place, in which case the position of the first Film web 1 can be controlled well.

The brake 6 is in the case shown a simple friction brake, Of course, by slowing down the rolling process the web supply 3 a braking effect can be achieved. This would have the further advantage that by friction as a result of Brake operation of the repeat not scratched or other Way can be damaged.

Claims (17)

1. A method for positioning webs of film, especially of a packaging device, wherein in a first web of film (1) moved in a direction of advance, goods are especially introduce into troughs of said first web of film (1), a second web of film (2) withdrawn from a supply of web (3) against the resistance of a brake is placed on the first web (1) and joined to the same, wherein the advance of the second web of film (2) is detected by a first recognition means (4) downstream of the supply of web (3) and is adjusted by varying the braking force of the brake (6) depending on the signal of the first recognition means (4) so that in each case a pattern repeat (7) as a defined area of the second web of film (2) comes to lie on the first web of film (1), especially on the troughs (8), characterised in that the exact position of the pattern repeat (7) relative to the first web of film is detected by means of a second recognition means (5) and in the event of dimensional deviations, the position of the first recognition means is changed relative to the direction of conveyance of the second web of film.
2. The method for positioning webs of film of a packaging device according to claim 1, characterised in that the second web of film (2) is provided with control marks which are recognised by the first recognition means (4) and the second recognition means (5).
3. The method for positioning webs of film of a packaging device according to claim 1 or 2, characterised in that the first web of film (1) and the second web of film (2) are each provided with at least one control mark per pattern repeat (7) and that the positional deviations of the control marks are determined by means of the second recognition means (5) to determine the relative position of the second web of film (2) to the first web of film (1).
4. The method for positioning webs of film of a packaging device according to one or more of the preceding claims, characterised in that the position of the first web of film (1) is determined by means of the second recognition means (5) using a defined edge of the trough (8) as a control edge, especially an optically detectable edge.
5. The method for positioning webs of film of a packaging device according to one or more of the preceding claims, characterised in that a sealing station is provided for joining first and second webs of film and the second recognition means is arranged before or after the sealing station.
6. The method for positioning webs of film of a packaging device according to one or more of the preceding claims, characterised in that the second web of film is joined to the first web of film under tensile stressing.
7. The method for positioning webs of film of a packaging device according to one or more of the preceding claims, characterised in that the extent of the positional correction of the first recognition means substantially corresponds to the dimensional deviation determined by the second recognition means.
8. The method for positioning webs of film of a packaging device according to one or more of the preceding claims, characterised in that the extent of the positional correction of the first recognition means is limited by the dimensional deviation as the maximum.
9. The method for positioning webs of film of a packaging device according to one or more of the preceding claims, characterised in that the positioning method is carried out periodically, wherein the period is longer than the processing time which elapses whilst a pattern repeat is conveyed from the first to the second detection means.
10. A packaging device, especially for carrying out a method for positioning webs of film according to one or more of the preceding claims, wherein a first web of film (1) is moved by an advance and a withdrawal device for withdrawing a second web of film (2) from the supply of web (3) and a first recognition device (4) arranged in the area of the supply of web (3) for detecting the movement of the second web of film (7) divided into individual pattern repeats, characterised in that in an area after the positioning of the second web of film (2) on the first web of film (1) a second recognition means (5) is provided to determine the exact position of the pattern repeat (7) relative to the troughs (8) in the first web of film (1), and a control system is provided to change the position of the first recognition means (5) relative to the direction of conveyance of the first web of film.
11. The packaging device according to the preceding claim, characterised in that the recognition means (4, 5) is a photocell which reacts to light reflected or transmitted by the web of film (1, 2).
12. The packaging device according to one or both of the preceding claims 10 or 11, characterised in that the second detection means has at least two sensors, for example, photocells.
13. The packaging device according to one or more of the preceding claims 10 to 12, characterised in that the recognition means (4) is an optical recognition means, a camera, especially a line scan camera.
14. The packaging device according to one or more of the preceding claims 10 to 13, comprising a welding device for joining the first web of film (1) to the second web of film (2), characterised in that the welding device or the sealing station can be triggered by a signal of the second optical recognition means (5).
15. The packaging device according to one or more of the preceding claims 10 to 14, characterised in that the position of the recognition means (4, 5) can be adjusted or set in the direction of advance especially according to the length of the pattern repeat or the spacing of two successive troughs.
16. The packaging device according to one or more of the preceding claims 10 to 15, characterised in that the first recognition means (4) is mounted in a carriage fashion on a guide track (10) and the control system acts on a drive which moves the first recognition means along the guide track.
17. The packaging device according to one or more of the preceding claims 10 to 16, characterised in that the position of the recognition means (4, 5) can be adjusted in a direction at right angles to the direction of advance.

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