Method for controlling the position of the edge of a web

Abstract

The present invention relates to a method for controlling the position of a bottom and / or top web on a packaging machine, wherein the bottom web is unwound from a supply roll and transported intermittently or continuously along the packaging machine, optionally forming packaging recesses into the bottom web in a forming station and then covering the bottom web, preferably the packaging recesses, with a packaging item being placed on it, and subsequently sealing a top web to the bottom web in a sealing station, wherein the bottom and top webs are each unwound from a supply roll.

Description

[0001] The present invention relates to a method for controlling the position of a bottom and / or top web on a packaging machine, wherein the bottom web is unwound from a supply roll and transported intermittently or continuously along the packaging machine, optionally forming packaging recesses into the bottom web in a forming station and then covering the bottom web, preferably the packaging recesses, with a packaging item being placed on it, and subsequently sealing a top web to the bottom web in a sealing station, wherein the bottom and top webs are each unwound from a supply roll.

[0002] In the generic process, the substrate web is typically transported along the packaging machine by two endless chains or toothed belts, each equipped with holders that grip the lateral edge of the substrate web. Those skilled in the art know that substrate webs have tolerances in their width and that they run approximately perpendicular to the transport direction, i.e., not parallel to it. In extreme cases, this can lead to the holders on the transport chains failing to grip the substrate web, or failing to grip it sufficiently, resulting in a production stoppage.

[0003] The object of the present invention was therefore to provide a method that does not have the disadvantage of the prior art.

[0004] The problem is solved by a method for controlling the position of a bottom and / or top web on a packaging machine, wherein the bottom web is unwound from a supply roll and transported intermittently or continuously along the packaging machine, optionally forming packaging recesses into the bottom web in a forming station and then filling the bottom web, preferably the packaging recesses, with a packaging item, wherein a top web is subsequently joined to the bottom web in a sealing station, wherein the bottom and top webs are each unwound from a supply roll, wherein the position of a reference point on the bottom and / or top web relative to a, preferably stationary, component of the packaging machine is detected and, based on this detection, the position of the bottom and / or top web is optionally changed transversely to its transport direction.

[0005] The present invention relates to a method carried out on a packaging machine in which a substrate web, in particular a plastic substrate web, preferably having a width between 200 mm and 1 m or more, is unwound from a supply roll and preferably transported intermittently / in cycles along the packaging machine in one transport direction. In an optional forming station, this substrate web is first heated, and packaging recesses are formed into the substrate web by means of a thermoforming tool. As a rule, several packaging recesses, arranged in a so-called format, are formed simultaneously and subsequently transported along the packaging machine simultaneously.The bottom web, preferably each packaging tray, is then filled / loaded with packaging material, preferably a format of packaging material, in particular a foodstuff such as sausage, ham, or cheese, and in a subsequent step, joined to a top web in a sealing station, the top web typically being sealed to the bottom web. It is understood that the packaging material can also be filled / placed into an unformed web. The completed packaging is then singulated. The top web is also unwound from a supply reel. With respect to the transport direction of the respective web, a dancer can be located downstream of at least one supply reel, which maintains the tension in the web at least substantially constant.

[0006] The web can be, for example, a paper, cardboard, and / or plastic film. The web can consist of several layers. The bottom and top webs typically differ in their structure. Each web can be transparent, translucent, or opaque. Each web can be printed. The bottom and / or top webs can be thermoformed.

[0007] The packaging produced using the inventive method may include an interlayer. The entire disclosure given for the top and bottom films and the control of their position transverse to the longitudinal direction of the packaging machine and / or transverse to the position of the bottom and / or top web also applies to the interlayer web.

[0008] According to the invention, at least one web of material has one or more reference points with which the transverse orientation of the respective web, i.e., perpendicular and / or horizontal to its transport direction and relative to a, preferably stationary, component of the packaging machine, can be detected. This makes it possible to detect whether the web runs laterally, i.e., transversely to the transport direction, meaning its transport direction is not parallel to the packaging machine, in particular its frame and / or its chain run, or whether the transport direction is parallel, but, for example, the supply roll of the web shows a lateral offset to the reference point. Alternatively or additionally, the reference points can be used to determine whether the nominal width of the web changes. Webs of material, especially low-quality webs, exhibit deviations from their parallelism relative to the transport direction.This deviation can also be determined using the reference point(s).

[0009] A possible reference point is, for example, at least one of the two edges of the web. Furthermore, preferred reference points are printed marks, preferably applied to the web at regular intervals. Additionally, a print, such as a logo, on the web can serve as a reference point.

[0010] A reference point according to the invention can have any shape and size. Preferably, the reference points are repeated at, in particular, regular intervals.

[0011] Based on this determination of the reference point's position, the position of the web is changed, particularly upstream of the reference point's detection location, perpendicular to the web's transport direction, if the determined reference point's position is outside a specified area. This change in the web's transverse position, relative to the web's transport direction, preferably occurs upstream of the location where the reference point's position is determined.

[0012] Changing the position of the web transversely to its transport direction can be accomplished in any manner known to those skilled in the art. Preferably, the supply roll is displaced along its axis of rotation. This can be achieved by providing the axis of rotation itself to be axially movable and / or by displacing the supply roll relative to the axis of rotation on which it is mounted. Normally, the axis of rotation is arranged horizontally and at a 90° angle to the transport direction of the web. However, to change the position of the web, the supply roll can be rotatably arranged about at least one axis, for example, a vertical and / or horizontal axis.

[0013] Alternatively or additionally, the web can, downstream of the supply reel, at least partially encircle one, preferably several, reels. These reel(s) are preferably located between the supply reel and the reference point detection point. To change the position of the web, these reel(s) are rotatable about an axis, in particular a vertical one.

[0014] Preferably, the reference point is detected by a sensor. Preferably, the sensor is an optical or ultrasonic sensor, or a tactile sensor, which, particularly with regard to its orientation perpendicular to the transport direction of the web, is preferably stationary. Furthermore, the sensor can, for example, be a sensor that emits waves towards the surface of the web, which are at least partially reflected by the web. The wave reflected by the web has a wavelength different from that of the emitted wave, and the degree of wavelength change is a measure of the change in the web's position (Doppler effect). The sensor preferably detects deviations of the reference point in two directions, for example, to the right and to the left perpendicular to the transport direction of the web. Its precise position perpendicular to the transport direction can preferably be input into a control system.Alternatively or additionally, its distance to a reference point on the packaging machine, for example its central axis in the longitudinal direction, the frame of the packaging machine, and / or the position of one or both chain runs, can be entered. The sensor can also be calibrated to a specific position of the reference point and then detects deviations from this position in two directions, even if its exact position has not been specified.

[0015] The sensor detects the reference point(s) after the respective web of material has been unwound. According to a preferred embodiment, the sensor is located immediately adjacent to the film roll, particularly when it has reached its maximum diameter. According to another preferred embodiment, the sensor is located in the entry area of ​​the chain run, i.e., where the chain grippers clamp the edge of the web. According to a further preferred embodiment, the sensor is located between the supply roll and the entry area of ​​the chain run.A combination of at least two sensors, preferably arranged at different positions between the supply roll and the entry area of ​​the warp thread, is further preferred. This allows for the detection of positional deviations at different locations, for example, to identify trends in the progression and / or effects of changes in position and to correct these changes accordingly. A sensor is also preferably provided upstream of the sealing station, ideally directly upstream of the sealing station, to detect the position of the top web relative to the position of the bottom web. This enables the control system to intervene in the event of significant deviations, for example, to align a printed image and / or a deep-drawn shape on the top web with the position of the packaged goods and / or the packaging recesses on / in the bottom web in the transverse direction.The expert understands that the position of the top layer web can also be recorded with more than one sensor and, if necessary, trends in the web's behavior.

[0016] The sensor signal is transmitted to a control system, which evaluates the signal and, if necessary, changes the position of the lower and / or upper web perpendicular to its transport direction.

[0017] Preferably, the web edge, one, in particular several print mark(s) and / or one, in particular several print image(s), in particular the edge of a print image and / or the surface of the web is used as a reference point.

[0018] Preferably, the control system detects the distance between the reference point and the center of the packaging machine, the frame of the packaging machine, and / or the chain run. These values ​​can then be used to control the position of the web of material perpendicular to its transport direction.

[0019] Preferably, the sensor is height- and / or length-adjustable. This allows, for example, the decreasing diameter of the supply roll to be taken into account, especially if the sensor is located in the area of ​​the supply roll.

[0020] Preferably, the inventive method is used to correct the course of the material web.

[0021] Furthermore, the inventive method can preferably compensate for deviations in the nominal width of the web. Alternatively or additionally, deviations in the parallelism of the web relative to its transport direction can be compensated. For example, the edges of the web are often not straight, but curved. These defects in the production of the web can be compensated for with the inventive method in such a way that there is no interruption of the packaging production process.

[0022] The method according to the invention is also suitable for compensating for inhomogeneities in the web. Such inhomogeneities, for example in the thickness and / or composition of the web, lead to web spreading, which can be compensated for with the method according to the invention.

[0023] The position of at least one reference point allows the transverse orientation of the web roll to be detected and corrected if necessary. This function is particularly useful during roll changes. The sensor detects the position, for example, one of the first reference points. The transverse orientation of the web roll is then corrected if needed. For example, the target position of the web roll and / or its actual position relative to a tolerance window is displayed, preferably after the web roll has been roughly positioned on its axis of rotation, the beginning of the web has been brought into its transfer position (e.g., by attaching it to the end of the previous web), the new web has been placed under minimum longitudinal tension, and the actual position of the web roll has been detected. The position of the web roll is then corrected, preferably until the displayed target position is at least approximately reached.The actual position is sufficiently accurate within the tolerance window. The target position and / or actual position can be displayed, for example, by means of an optical display on or near the axis of rotation of the web roll and / or on the control panel and / or on a display. Preferably, before inserting a film roll, the axis of rotation is first brought into a position, preferably centered with respect to the adjustment travel of the actuators, based on the target position of the web roll, such that the normally limited adjustment travel of the actuators allows axial adjustment of the axis of rotation or the supply roll relative to the axis of rotation without exceeding the limits of the adjustment travel.

[0024] Preferably, a trend analysis is performed using the data acquired by the sensor. This analysis preferably determines whether there is a preferred direction in the trend. Based on this analysis, modifications to the packaging machine can then be made, for example. The analysis can also be used to investigate whether the trend is batch-dependent and, if so, to determine, in consultation with the respective manufacturer, what causes the trend and how this error can be corrected. A trend can be caused, for example, by inconsistent web thickness and / or uneven stretching of the web. The trend analysis can also indicate fluctuations in web width and / or that the web edges are not parallel to their transport direction, but rather curved, particularly sinusoidal or cosine-shaped.

[0025] The data collected by the sensor(s) can also be used to generate an error message and / or to stop the machine. For example, an error message or a machine stop can occur if: The system will shut down if the lateral adjustment range of the control system has been reached or exceeded, a detected trend cannot be stopped or reversed, the sensors detect that a web of incorrect width has been applied, the recorded data indicates that the web is of inferior quality, and / or the recorded data indicates that the web was not correctly mounted on the shaft of the packaging machine, for example, in an incorrect axial position.

[0026] Preferably, error messages are recorded and analyzed per unit of time. This analysis can be used to prevent errors and / or improve the quality of the web. For example, the tolerance in the web can be reduced and / or its parallelism to the direction of transport improved.

[0027] Preferably, a sensor is positioned at both edges of the web. This allows, for example, the width of the web to be checked, particularly during unwinding, and repeatedly. The two sensors can also detect any lack of parallelism to the web's direction of travel. If possible, this defect is then corrected.

[0028] The inventions are described below based on the Figures 1 to 4These 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 a first embodiment of the method according to the invention. Figure 3 shows detail Z Figure 2 Figure 4 shows the unwinding of the material web by a packaging machine.

[0029] Figure 1Figure 1 shows the packaging machine 1 according to the invention, which here comprises a thermoforming station 2, a filling station 7, and a sealing station 15. A substrate web 8, here a plastic substrate web 8, is unwound from a supply roll 22 and transported intermittently along the packaging machine from right to left in its transport direction 40. With each cycle, the substrate web 8 is advanced by one format length / feed length. For this purpose, the packaging machine has two transport means 24 (in Figure 1(not shown), in the present case, each has two endless chains, two chain runs, arranged to the right and left of the underlayer web 8. 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 inlet area and / or in the outlet area can be connected to each other, preferably by a rigid shaft. Each transport element has a plurality of clamping elements 42 (see figure). Figure 3) which clamps the underlayer web 8 in the infeed area 19 and transmits the movement of the transport means to the underlayer web 8. In the outfeed area of ​​the packaging machine, the clamping connection between the transport means and the underlayer web 8 is released again. Downstream of the infeed area 19, a heating element 13 may be provided to heat the web 8, particularly when it is stationary. In the optional deep-drawing station 2, which has an upper die 3 and a lower die 4 having the shape of the packaging recess to be produced, the packaging recesses 6 are formed into the optionally heated 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 trays or a flat underlayer web are filled / loaded with the product 16 in the filling station 7. In the subsequent sealing station 15, which also consists of an upper tool 12 and a vertically adjustable lower tool 11, an overlayer web 14 is bonded to the underlayer web 8 by sealing. This transfers the movement of the underlayer web 8 to the overlayer web 14. In the sealing station, the upper tool and / or the lower tool are lowered and / or raised before and after each web transport. The overlayer film 14 can also be guided in transport devices or transported by conveyor chains, whereby these transport devices then only extend in front of the sealing station and, if necessary, downstream. Otherwise, the descriptions given for the transport devices of the underlayer film apply.The top film can also be heated with a heating medium and deep-drawn. For sealing, a heated sealing frame, for example, is provided as the lower tool 11. This frame has an opening for each packaging cavity into which the packaging cavity dips during sealing, i.e., during the upward movement of the lower sealing tool. For sealing, the top and bottom webs are pressed together between the upper and lower tools 12, 11 and bond under the influence of heat and pressure. After sealing, the tools 11, 12 are moved apart vertically again. A dancer 20, here a rotary dancer, can be provided between the supply roll 21 and the sealing tool to keep the web 14 at a constant tension. Those skilled in the art understand that several top webs / interlayers may be present, for example, in a multi-layer package or a package with multiple top webs.Preferably, a dancer is provided along each top film. Those skilled in the art will further understand that a dancer may also preferably be provided in the area of ​​the bottom film, preferably downstream of the supply roll 22. Preferably, the dancer is a linear dancer. Before and / or during the sealing of the top film to the bottom film, gas exchange preferably takes place in each packaging cavity. For this purpose, the air present in the packaging cavity is first partially extracted and then replaced by an exchange gas. For this, holes are made in the bottom film in the area of ​​the transport chains for each format, through which the air between the webs 8, 14 is extracted and the exchange gas is then blown in. Further along the packaging machine, the finished packages are singulated, which in this case is done with the cross cutter 18 and the longitudinal cutter 17.In the present case, the cross cutter 18 can also be raised or lowered by means of a lifting device 9.

[0030] Preferably, at least one supply roll 21, 22 is driven by a motor, in particular a torque motor, such that the required feed length of the respective web is unwound from the roll without the tensile force of the two transport means, the transport chains, and / or the tensile force of the underlayer web being significantly transferred to the overlayer web. This results in the respective web being subjected to only a comparatively low tension, and thus being only slightly pre-stretched and wrinkling.

[0031] The inventive method can also be used to process comparatively thin webs of material and / or webs of material with low quality, particularly with regard to homogeneity in terms of shape and / or composition.

[0032] Preferably, the rotation of the motor driving the supply roll 21, 22 is controlled / regulated by a computer system, which may be part of the packaging machine or part of a line control system. In particular, the rotational speed of the supply roll is controlled such that the unwound web length corresponds to the feed rate and / or that the speed profiles of the web unwinding and / or the feed rate of the transport means, especially the transport chains, are at least substantially identical. The current diameter or weight of the supply roll is taken into account in this process.

[0033] Preferably, the dancer is equipped with a motion sensor, for example a rotary encoder or a linear encoder, which can be used to determine the stored web length corresponding to the dancer's movement. This information can be used, for example, to determine the diameter of the supply roll.

[0034] Preferably, a dancer is provided in the area of ​​the underside and the topside web. Preferably, the supply reel of the underside and / or the topside web is driven by a motor such that the unwinding of the respective web is carried out by a motor drive in such a way that the respective web is only minimally tensioned.

[0035] Figures 2 and 3 show a first embodiment of the method according to the invention, wherein in Figure 3 a detail from Figure 2As illustrated, a web of material 8, 14 is unwound from a reel 20, 22 and transported in a transport direction 40. For various reasons, the web of material may deviate 46 from its transport direction 40, which is compensated for by the method according to the invention. For this purpose, the packaging machine has a sensor 39, which is preferably stationary and mounted on the machine frame, and which detects the position of one or more reference points. Based on this measurement, a control system can determine whether the web of material is deviating and / or whether the reference point is located within an acceptable range relative to a component of the packaging machine. The reference point is, for example, the web edge 38, a print mark, or a printed image.For example, the distance 43 between the reference mark and the central axis 41 of the packaging machine is determined, and / or the distance 44 between the reference mark, here the edge of the web, and the chain run and / or its gripper 42 is determined. Alternatively or additionally, the distance of the reference mark to the machine frame 28 can also be determined. Based on the signal from this sensor 39, a control system corrects the position of the film web 8, 14 perpendicular to its transport direction. This can be done, for example, using a device that uses... Figure 4 is described in more detail. Preferably, the correction takes place upstream of sensor 39.

[0036] Figure 4 shows another embodiment of the packaging machine, essentially based on the designs according to Figure 1Reference can be made to the following. The supply roll 21, 22 is mounted on a shaft 23, preferably non-rotatably and / or axially non-displaceable. As the lower and / or upper web 8, 14 unwinds, the shaft 23 rotates in the direction indicated by arrow 40. The shaft 23 is preferably rotatably and optionally also longitudinally displaceably mounted at both ends by means of a bearing 31. A bearing 31 can, for example, be provided on the housing of the web unwinder or the packaging machine. For longitudinal displacement, the bearings 31 can be designed as sliding bearings. The shaft 23 is preferably driven by a motor 25. A coupling 26, for example a sliding coupling or a gearbox, preferably a sliding gearbox, can be provided between the motor 25 and the shaft 23.According to the invention, the shaft 23 alone and / or the frame 29 on which the shaft 23 of the web unwinding system is mounted is provided to be longitudinally displaceable, as symbolized by arrow 37, and / or transverse to the transport direction 40 of the web. For this purpose, for example, the frame 29 on which the shaft 23 and the motor 25 are mounted is provided to be longitudinally displaceable, for example along a guide 32. The movement 37 is effected, for example, by an adjustment drive 35, which moves at least the shaft 23 along its central axis, but preferably also the frame 29. Those skilled in the art understand that the drive motor 25 can also be moved during the longitudinal displacement, but this is not a requirement. The bearings 32-34 are preferably arranged on a base frame 28, which is particularly stationary.

[0037] Preferably, the packaging machine according to the invention has a sensor 39, which is preferably a web edge detection device. This web edge detection device 39 detects the position of the web edge, for example, relative to the frame of the packaging machine or another preferably stationary location. If the web edge is located beyond a desired limit, the adjustment drive 35 is preferably activated, which then moves the shaft 23 or the frame 29 in the direction symbolized by the arrows 37 until the web is again within the desired limit.

[0038] When starting up or changing the supply roller, the sensor signal can also be used to correct the axial position of the roller on the shaft 23. Reference symbol list:

[0039] 1 Packaging machine 2 Forming station, thermoforming station 3 Upper tool of the thermoforming station 4 Lower tool of the thermoforming station 5 Lifting table, carrier of a tool of the sealing, thermoforming station and / or the cutting unit 6 Packaging trough 7 Filling station 8 Web, bottom web, web 9 Lifting device 10 Drive 11 Lower tool of the sealing station 12 Upper tool of the sealing station 13 Heating element 14 Top web, lid film, web 15 Sealing station 16 Product to be packaged 17 Longitudinal cutter 18 Cross cutter 19 Infeed area 20 Dancer 21 Supply roll of the top web 22 Supply roll of the bottom web 23 Shaft of the supply roll 24 Chain 25 Motor, torque motor 26 Coupling, sliding coupling 27 Motor shaft 28 Base frame, packaging machine 29 Support, sliding frame 30 Door, bearing housing Frame 31 Bearing, plain bearing 32 Guide, guide rod 33 Bearing, plain bearing 34 Bearing block, bearing housing 35 Adjustment drive, motor, geared motor, spindle motor, servo motor 36 Spindle, shaft, adjusting device,37 Adjustment direction, sliding direction 38 Reference point, web edge, material web edge, material web edge 39 Sensor, web edge detection device 40 Transport direction, material web direction, material web direction 41 Center axis of the packaging machine 42 Clamping device, gripper 43 Distance material web edge to packaging machine center 44 Distance material web edge to chain 45 Distance material web edge to base frame 46 Material web path,

Claims

1. A method for controlling the position of a sub-web (8) on a packaging machine, wherein the sub-web (8) is unwound from a supply roll (22) and transported intermittently or continuously along the packaging machine by means of two transport means (24) designed as chain strands, which are arranged to the right and left of the sub-web (8) and each have a plurality of clamping means (42) designed as grippers, which clamp the sub-web (8) in the infeed area of ​​the packaging machine and transmit the movement of the transport means (24) to the sub-web (8), and wherein, optionally, packaging recesses (6) are formed into the sub-web (8) in a forming station (2) and the sub-web, preferably the packaging recesses, are then covered with a packaging item (16), wherein subsequently, in a sealing station (15), a top web (14) is joined to the sub-web (8).wherein the lower and upper webs (8) are each unwound from a supply roll (21, 22), characterized by the fact that the position of a reference point (38) on the underlay web (8) relative to a stationary component of the packaging machine is detected and, based on this detection, the position of the underlay web (8) is changed transversely to its transport direction, wherein a sensor detects the reference point (38) after the underlay web (8) has been unwound, wherein the sensor is located in the inlet area of ​​the chain run, where the grippers of the chain clamp the edge of the underlay web (8).

2. Method according to claim 1, characterized by the fact that The reference point (38) is one of the two edges of the substrate web (8), a print mark and / or print image, in particular the edge of a print image.

3. Method according to one of claims 1 or 2, characterized by the fact thatthe distance between the reference point and the center (41) of the packaging machine, the frame (28) of the packaging machine and / or the chain run (24) is determined.

4. Method according to any of the preceding claims, characterized by the fact that The sensor is height- and / or length-adjustable.

5. Method according to any of the preceding claims, characterized by the fact that the position of the sub-web (8) upstream of the detection point of the reference point perpendicular to the transport direction of the sub-web (8) is changed if the determined position of the reference point is outside a specified area.

6. Method according to any of the preceding claims, characterized by the fact that the supply roll is moved along its axis of rotation.

7. Method according to claim 6, characterized by the fact that the axis of rotation of the supply roller is designed to be axially movable.

8. Method according to claim 6, characterized by the fact thatthe supply roll is moved relative to the axis of rotation on which it is mounted.

9. Method according to any one of claims 1 to 5, characterized by the fact that The underlayer web (8) extends downstream from the supply roll and at least partially encircles several rolls, the rolls being rotatable about an axis to change the position of the underlayer web (8).

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