Packaging machine for producing packaging from printed webs of material.

Abstract

A method for producing packaging, in which a printed sub-web (8) bearing print marks is unwound intermittently from a web roll (21) in a running direction (27) and fed to a forming station (2) in which the packaging recess (6, 6') is formed into the sub-web, wherein after unwinding and before forming the sub-web the position of the print mark in the running direction (27) of the sub-web is determined by a sensor (26) and the elongation of the sub-web between the web roll (21) and its connection with a transport means (29), in particular a transport chain, and / or between the web roll (21) and the forming station (2) is changed according to the signal of the sensor (26) by blocking the web roll (21, 28) after unwinding a cycle length.

Description

The present invention relates to a method for producing packaging in which a printed substrate web, bearing print marks, is unwound intermittently from a web roll in one direction and fed to a forming station where a packaging recess is formed into the substrate web. The present invention further relates to a packaging machine in which a substrate web bearing print marks is unwound intermittently from a web roll, and in which a forming station forms packaging recesses into the substrate web. A sealing station, which bonds a top layer web to the substrate web, and a cutting device, which separates the completed packaging from the substrate webs, are also included. Such a process or packaging machine is well known from the prior art, for example, DE 103 19 420 A1, DE 27 15 386 A1, US 3 762 125 A, DE 22 54 715 A, CH 447 924 A, and DE 72 11 900. These packaging machines are referred to as form-fill-seal (FFS) packaging machines or thermoformers. They are used, for example, for packaging food products. Currently, there is a need to use printed films, but there is also a desire to process shrink films, i.e., films that contract under the influence of heat, and / or very thin, i.e., highly elastic, films. When processing printed films in particular, the printed image must be positioned precisely within the area of ​​the packaging to be produced. For this purpose, the web of material has a printed mark that is used to position the web of material.For example, DE10319420A1 proposes stretching the lid film with a movable brake until it is positioned precisely on a packaging recess. However, this state of the art has the disadvantage that this technology is not suitable for very thin, i.e., very elastic and / or shrinkable films, because these films often tend to exhibit pronounced rubber-band-like behavior. The object of the present invention was therefore to provide a method and a packaging machine that do not have the disadvantages of the prior art. The problem is solved by a method for producing packaging in which a printed sub-web, bearing print marks, is unwound intermittently from a web roll in one direction and fed to a forming station in which the packaging recess is formed into the sub-web, in which, after unwinding and before forming the sub-web, the position of the print mark in the direction of travel of the sub-web is determined by a sensor and the elongation of the sub-web between the web roll and its connection with a transport means, in particular a transport chain, and / or between the web roll and the forming station is changed according to the signal from the sensor. The present invention relates to a method for manufacturing packaging, in particular plastic packaging. In the method according to the invention, a printed substrate web, preferably having one print mark per image, is unwound intermittently from a web roll in the direction of travel and fed to a forming station. In the forming station, a packaging cavity is formed into the substrate web, for example by thermoforming. The substrate web, which is preferably a plastic film web, is particularly preferably heated during this process. This packaging cavity is then filled with the packaged goods, for example, food products, and then sealed with a surface web, preferably also a plastic film, which is attached to the substrate web, in particular by means of a material bond, for example by sealing.Before the packaging tray is closed, a vacuum can optionally be drawn and / or a gas exchange can be carried out. The completed packages are then separated. These packaging machines operate intermittently according to the invention; that is, for example, the underlayer web is unwound from a web roll by a cycle length required to produce a format, and the underlayer web then remains stationary until the respective format is formed into the underlayer web, or the underlayer web is filled and / or sealed with an overlayer web and / or the individual packages are separated. The transport of the underlayer web is therefore not continuous but intermittent. According to the invention, after unwinding and before forming the underlayer web, the position of the print mark in the direction of travel of the underlayer web is determined by a sensor, for example a camera, i.e. the sensor checks, for example, whether the print mark has been transported past it or not, or is located in the area of ​​the sensor, when the underlayer web is advanced by a cycle length.Depending on the signal sent by the sensor to a machine control system, the underlayer web, particularly the section between the web roll and the forming station, is then stretched, relaxed, or its existing stretch is maintained. Preferably, however, this section is stretched, slightly stretched, or stretched even less—always by a certain amount more or less. This is made possible by the web and / or the printed image being produced slightly shorter, and the shorter length being used as a margin for stretching. For example, the control system can be configured so that the underlayer web is not stretched, or not stretched additionally, if the print mark is located precisely within the sensor's range.If the print mark has already passed the sensor before the incremental feed has finished, the substrate web is stretched until the print mark is within the sensor's range. If the feed has already finished by one increment and the print mark has not yet passed the sensor, the stretch of the film is reduced, for example, until the print mark has moved downstream far enough for the sensor to detect it. A person skilled in the art recognizes that, consequently, the stretch of the substrate web can differ for each increment. A person skilled in the art recognizes that the stretching does not change the position of the print image currently located within the forming station, but rather the position of a print image located at least one, preferably two or more, increments upstream of the forming station.Preferably, the set elongation of the respective cycle length of the underlayer web is fixed before it reaches the forming station. The underlayer and / or the toplayer is preferably a plastic film film, in particular a shrinkable plastic film film and / or a plastic film film having a film thickness preferably < 120 µm, particularly preferably < 80 µm. The disclosure made relating to this process applies equally to the other objects (process and packaging machines) of the present invention and vice versa. Another solution to the problem or a preferred embodiment of the method described above is a method for producing packaging in which a packaging recess is closed with a top web having printed marks, wherein the top web is unwound intermittently from a web roll and bonded to a bottom web in a sealing station and transported further intermittently by the bottom web, wherein, preferably at each cycle, the position of the printed mark in the direction of travel of the top web is determined by a sensor and the elongation of the top web is changed according to the signal of the sensor, from the film roll to the sealing station. This embodiment of the present invention has the advantage that the printed images can be positioned very precisely on surface webs that contract and expand like a rubber band due to their elasticity. The inventive method does not require a film brake such as that disclosed, for example, in DE10319420A1. This inventive or preferred subject matter of the present invention relates to a method for producing packaging in which a packaging tray, in particular a filled packaging tray, is closed with a surface web which also has printed marks. The top layer web can be shaped or stretched before being bonded to the bottom layer web. Stretching has a particularly positive effect on the shrinkage capacity of the top layer web. Furthermore, it is conceivable that the surface web is held before being joined to the underlayer web, i.e., its shape and / or elongation is fixed, and / or that it is additionally transported by a conveying device. Both functions can be performed, for example, by conveying chains arranged to the right and left of the surface web and equipped with means by which the surface web can be gripped reversibly. According to the invention, the top web is unwound intermittently from a web reel and bonded to the bottom web in a sealing station. The intermittent transport of the bottom web also drives the top web intermittently, thus advancing it further. According to the invention, it is provided that, preferably at each cycle, the position of the print mark in the direction of travel of the top layer web is determined by a sensor, and the tension of the top layer web is adjusted according to the sensor signal from the film roll to the sealing station. In other words, at least the entire unwound top layer web that is not yet attached to the bottom layer web or whose tension is not yet fixed is stretched during this process, whereby the stretching can be carried out analogously to the method described for stretching the bottom layer web. Preferably, the position of the printed image on the top layer web that is to be sealed onto the bottom layer web at this cycle is set in this process. The stretching of the top layer web preferably takes place after the feed of the bottom layer web has already been completed for the respective cycle. The disclosure made relating to this process applies equally to the other objects (process and packaging machines) of the present invention and vice versa. The following statements apply in particular to both methods according to the invention, but also equally to the packaging machines according to the invention. Preferably, the web roll of the top web and / or the bottom web is blocked after or during the unwinding of a cycle length, so that it cannot unwind any further. It is quite conceivable that, particularly during the initial setup of a packaging process, the elongation of the respective web varies with each cycle length. Preferably, however, the method according to the invention is programmed to be self-learning, so that after a few cycle lengths, for example, it has adapted to the respective process conditions and / or a new web roll, and then the elongation of the respective web no longer needs to be varied significantly. Preferably, after unwinding, the underlay web is connected to a transport device and carried by it, with the underlay web being stretched before being connected to the transport device. The transport device can, for example, be an endless chain positioned to the right and left of the underlay web, each equipped with grippers that grasp the underlay web at regular intervals in the infeed area of ​​the packaging machine and transport it along the machine. In the outfeed area, this connection between the underlay web and the transport devices is then released. Preferably, these transport means fix the elongation imposed on the underlayer web during the respective film feed, so that it is maintained along the entire packaging machine, but especially during the forming of the packaging troughs, and so that it can vary from cycle length to cycle length. According to another preferred embodiment, the amount by which the cycle length of the respective web of goods is to be stretched is infinitely adjustable. The problem is further solved with a packaging machine in which a substrate web bearing printed marks is unwound from a web roll intermittently, a thermoforming station forms packaging recesses in the substrate web, a sealing station attaches a top web to the substrate web in a material-bonded manner, and a cutting device separates the completed packaging from the substrate webs, the cutting device having a sensor that detects the printed marks on the substrate web and whose signal controls a means that stretches the substrate web section by section. The descriptions given for this packaging machine apply equally to the methods according to the invention and to the further packaging machine according to the invention, and vice versa. According to the invention, the packaging machine has a sensor that detects the print marks on the substrate web and whose signal is used to control a means that stretches the substrate web section by section. The stretching is adjusted so that the print mark assumes a specific position relative to the stationary sensor. The means that stretches the underlayer web can, for example, be a controlled, driven dancer, which is designed to rotate about an axis, and in which the change of the angle of rotation results in an increasing or decreasing stretching of the web. Preferably, the packaging machine includes a transport means, in particular transport chains, that fixes the underlayer web and transports it along the packaging machine. The means for changing the stretch of the underlayer web is provided before the web is gripped by the transport means, i.e., upstream of the transport means. According to a further or preferred embodiment of the packaging machine according to the invention, it has a sensor that detects print marks on the top web and whose signal controls a means that stretches the top web so that the printed images present on it are arranged exactly over a packaging recess and can be connected there with the bottom web, for example by sealing. The descriptions given for this packaging machine apply equally to the methods according to the invention and to the further packaging machine according to the invention, and vice versa. The inventions are explained below with reference to Figures 1 and 2. These explanations are merely exemplary and do not limit the general concept of the invention. The explanations apply equally to all aspects of the present invention. Figure 1 shows the packaging machine according to the invention. Figure 2 shows the means for stretching the substrate web. Fig. 1 shows the packaging machine 1 according to the invention, which comprises a thermoforming station 2, a filling station 7, and a sealing station 19. A substrate web 8, here a printed, preferably shrinkable plastic film web 8, the so-called substrate web, is unwound from a supply roll and transported intermittently along the packaging machine according to the invention from right to left. At each cycle, the substrate web 8 is advanced by a format length, which is also referred to as the cycle length. For this purpose, the packaging machine has two transport means, in this case two endless chains, arranged to the right and left of the substrate web. At least one gear is provided for each chain at both the beginning and the end of the packaging machine, around which the respective chain is deflected. At least one of these gears is driven.The gears in the infeed and / or outfeed sections can be connected to each other, preferably by a rigid axle. Each transport element has a plurality of clamping elements that grip the web 8 in the infeed section and transmit the movement of the transport element to the underfeed web 8. In the outfeed section of the packaging machine, the clamping connection between the transport element and the web 8 is released. In the thermoforming station 2, which has an upper die 3 and a lower die 4 having the shape of the packaging tray to be produced, the packaging trays 6 are formed into the web 8. The lower die 4 is arranged on a lifting table 5, which, as symbolized by the double arrow, is vertically adjustable. Before each web feed, the lower die 4 is lowered and then raised again.In the next stage of the packaging machine, the packaging cavities are filled with the product 16 in the filling station 7. In the subsequent sealing station 19, which also consists of an upper tool 12 and a vertically adjustable lower tool 11, a top web 14 is bonded to the bottom web 8, preferably by sealing. By sealing the top web to the bottom web, the bottom web drives the top web and also pulls it off the supply roll 28 in increments. In the sealing station, the upper tool and / or the lower tool are also lowered or raised before and after each film transport. Before sealing the top web 1 to the bottom web 8, a certain vacuum may be created in the filled packaging cavity and / or a gas exchange may take place. The creation of the vacuum or...The gas exchange preferably takes place while the respective packaging tray is within the sealing station, preferably immediately before the sealing tools 11, 12 are pressed against each other. The top web 14 can also be guided or transported in a transport and / or fixing device. The descriptions given for the transport device of the bottom web also apply to the top web. Furthermore, the top web can also be deformed and / or stretched. This deformation / stretching is preferably fixed by the transport / fixing device. In the further course of the packaging machine, the finished packages are separated, which in this case is done with the cross cutter 25 and the longitudinal cutter 23. In this case, the cross cutter 25 can also be raised or lowered by a lifting device 9. Fig. 2 shows an example of a means for stretching the underlayer web 8, whereby this means can be used analogously to stretching the toplayer web 14. Fig. 2 shows the infeed area 24 of the packaging machine 1 according to the invention. In this area, a web of material 21, in this case a film roll, is rotatably arranged on a rotary axis 22. As indicated by the arrow, the underlayer web 8 is unwound from the web roll 21 intermittently by one cycle length and then gripped by transport means 29, here endless transport chains with grippers, which transport the underlayer web along the packaging machine intermittently, i.e., with intermittent advancement of the underlayer web, by one cycle length at a time. Before the underlayer web is gripped by the transport means, it passes a stretching device 13, here a dancer, with which the unwound section of the web located between the transport means 29 and the roll 21 can be stretched.Furthermore, the packaging machine according to the invention has a sensor 26 in the infeed area, which makes it possible to detect print marks that specify the position of the respective printed image on the substrate web. The packaging machine according to the invention does not have a film brake 23, as is required, for example, in the prior art, in particular in DE10319420A1. In the present case, the dancer has several rollers 18, 20 which deflect the substrate web 8. The rollers 18 are provided on the actual dancer, which is rotatably arranged about a pivot axis 17. On its side opposite the pivot axis or at an intermediate position, the dancer has a controlled drive 30, in the present case a linear drive, with which the angular position of the dancer can be continuously adjusted.This makes it possible to continuously stretch the entire web area between the transport vehicle and the roller from no stretching to the plasticity limit of the film web and beyond. This stretching is used to position the respective print mark relative to the sensor 26 so that this printed image assumes the desired position in the forming station, i.e., that the formed packaging recess corresponds, as desired, to the printed image printed on the web. The control can be implemented as follows: After each feed, the rotation of the web roller 21 is preferably blocked. If, at the end of a feed, the print mark is located directly under the sensor 26, the dancer drive is not activated, i.e., the dancer remains in its current position. However, if the feed is completed without the sensor 26 having detected the print mark, i.e.,Before the print mark has passed the sensor, drive 30 is activated to reduce the web tension; in this case, the dancer is rotated counterclockwise. This causes the print mark, located upstream of sensor 26, to move towards the sensor. The dancer continues to move until sensor 26 detects the print mark. Conversely, if the print mark has already passed the sensor before the transport cycle is complete, the web tension is increased. This causes the print mark to move backward until it is within the range of sensor 26. Depending, for example, on the material properties of the substrate web used, preferably in webs that do not allow a rapid reduction, or possibly no reduction at all, of the previously experienced elongation, the control can also be implemented as follows. After each feed, the rotation of the web roller 21 is preferably blocked. If, at the end of a feed, the print mark is located directly under the sensor 26, the drive of the dancer is not changed; that is, the elongation that the dancer causes on the substrate web remains at its current level. However, if the feed is completed without the sensor 26 having detected the print mark, i.e., without the print mark having passed the sensor, the drive 30 is changed so that the elongation of the substrate web decreases; that is, in this case, the dancer is rotated counterclockwise.This causes the relevant print mark, which would otherwise be located upstream of sensor 26 without adjusting the tension, to move towards the sensor, but only during the next feed cycle. In the preferably self-learning programmed method, the dancer is moved intermittently until sensor 26 detects the print mark. Conversely, if the print mark has already passed the sensor before the transport cycle is complete, the tension of the underlayer web is increased. This causes the print mark to move backward during the next feed cycle until it is located within the area of ​​sensor 26.The person skilled in the art may expect that, particularly during the initial setup of the packaging process, fluctuations in the position of the print mark relative to the sensor will occur over several feed cycles until the packaging process proceeds as a reliable procedure with preferably only minor fluctuations in the position of the print mark, which then usually result from manufacturing-related fluctuations in the web quality. The person skilled in the art recognizes that the same arrangements can also be used to stretch the top web, whereby in this case the stretching is imprinted on the film web section which has already been unwound but is not yet connected to the bottom web or the area has already been unwound but is not yet fixed. Reference symbol list: 1 Packaging machine 2 Thermodrawing station 3 Upper tool of the thermodrawing station 4 Lower tool of the thermodrawing station 5 Lifting table, carrier of a tool of the sealing, thermodrawing station and / or the cutting unit 6, 6' Packaging trough 7 Filling station 8 Underweb, underweb 9 Lifting device 10 Frame 11 Lower tool of the sealing station 12 Upper tool of the sealing station 13 Means, stretching agent, dancer 14 Topweb, topweb, lid film 15 Format 16 Packaging item 17 Rotary axis 18 Roll 19 Sealing station 20 Roll 21 Web roll, film roll 22 Rotary axis, preferably with brake 23 Film brake (state of the art) 24 Infeed area 25 Cutting unit 26 Sensor 27 Direction of travel of the underweb 28 Web roll, film roll 29 Transport means, gear for guiding and / or transporting the transport chain 30 Drive of the dancer, linear drive

Claims

A method for producing packaging, in which a printed sub-web (8) having print marks is unwound intermittently from a web roll (21) in a direction of travel (27) and fed to a forming station (2) in which the packaging recess (6, 6') is formed into the sub-web, wherein after unwinding and before forming the sub-web the position of the print mark in the direction of travel (27) of the sub-web is determined by a sensor (26) and the elongation of the sub-web between the web roll (21) and its connection with a transport means (29), in particular a transport chain, and / or between the web roll (21) and the forming station (2) is changed according to the signal of the sensor (26) by blocking the web roll (21, 28) after unwinding a cycle length. A method for producing packaging, preferably according to claim 1, in which a packaging recess (6, 6') is closed with a top web (14) having printed marks, wherein the top web is unwound intermittently from a web roll (28) and bonded materially to a bottom web (8) in a sealing station (19) and transported further intermittently by the bottom web, wherein, preferably at each cycle, the position of the printed mark in the direction of travel of the top web is determined by a sensor (26) and the elongation of the top web is changed according to the signal of the sensor (26), from the web roll (28) to the sealing station (19), by blocking the web roll (21, 28) after unwinding a cycle length. Method according to one of the preceding claims, characterized in that the elongation varies per cycle. Method according to one of the preceding claims, characterized in that the web of goods is connected to a transport means after unwinding and is transported by it, wherein the stretching of the sub-web of goods takes place before its connection to the transport means. Method according to one of the preceding claims, characterized in that the elongation of the web of goods is fixed by the means of transport. Method according to one of the preceding claims, characterized in that the amount of elongation of the web (8, 14) is continuously adjusted.

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