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 lower and / or upper product web on a packaging machine, wherein the lower product web is unrolled from a supply roll and transported intermittently or continuously along the packaging machine and, if appropriate, packaging troughs are formed into the lower product web in a forming station and the lower product web, preferably the packaging troughs, are then covered with a packaging product, wherein subsequently, in a sealing station, an upper product web is sealed to the lower product web, wherein the lower and upper product webs are each unrolled from a supply roll.

Description

[0001] The present invention relates to a method for controlling the position of a lower and / or upper product web on a packaging machine, wherein the lower product web is unrolled from a supply roll and transported intermittently or continuously along the packaging machine and, if appropriate, packaging troughs are formed into the lower product web in a forming station and the lower product web, preferably the packaging troughs, are then covered with a packaging product, wherein subsequently, in a sealing station, an upper product web is sealed to the lower product web, wherein the lower and upper product webs are each unrolled from a supply roll.

[0002] In this generic process, the bottom web of fabric is usually transported along the packaging machine using two endless chains or endless toothed belts, each of which has holders that hold the side edge of the bottom web. Experts know that webs of fabric have tolerances in their width and that webs run approximately transversely to the direction of transport, i.e., are not aligned parallel to their direction of transport. In extreme cases, this can lead to the holders on the transport chains no longer gripping the web of fabric or not gripping it sufficiently, resulting in a production stoppage.

[0003] It was therefore the object of the present invention 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 lower and / or upper web on a packaging machine, wherein the lower web is unwound from a supply roll and transported intermittently or continuously along the packaging machine and, if appropriate, packaging troughs are formed in the lower web in a forming station and the lower web, preferably the packaging troughs, are then covered with a packaged item, wherein a top web is subsequently connected to the lower web in a sealing station, wherein the lower and upper webs are each unwound from a supply roll, wherein the position of a reference point on the lower and / or upper web relative to a preferably stationary component of the packaging machine is detected and, based on this detection, the position of the lower and / or upper web transverse to its transport direction is changed if necessary.

[0005] The present invention relates to a method carried out on a packaging machine, in which a base web, in particular a plastics material web, which preferably has a width between 200 mm and 1 m or more, is unwound from a supply roll and preferably transported intermittently / cyclically along the packaging machine in a transport direction. In a forming station, if present, this base web is then first heated, and packaging cavities are formed into the base web by means of a thermoforming tool. As a rule, several packaging cavities, arranged in a so-called format, are formed simultaneously and subsequently transported simultaneously along the packaging machine.Subsequently, the lower web of goods, preferably each packaging trough, is filled / lined with a packaged product, preferably a format of packaged goods, in particular a food product such as sausage, ham or cheese, and in a next step is connected to an upper web of goods in a sealing station, wherein the upper web of goods is generally sealed to the lower web of goods. Those skilled in the art will understand that the packaged product can also be filled / placed in an unformed web of goods. The thus finished packaging is then separated. The upper web of goods is also unwound from a supply roll. With respect to the transport direction of the respective web of goods, a dancer can be located downstream of at least one supply roll, which keeps the tension in the web of goods at least substantially constant.

[0006] The material web can be, for example, a paper, cardboard, and / or plastic film web. The material web can consist of several layers. The lower and upper webs usually differ in their structure. Each material web can be transparent, translucent, or opaque. Each material web can be printed. The lower and / or upper webs can be deep-drawn.

[0007] The packaging produced using the method according to the invention may have an intermediate layer. The entire disclosure made regarding the top and bottom films and the control of their position transversely to the longitudinal direction of the packaging machine and / or transversely to the position of the bottom and / or top product web also applies to the intermediate layer web.

[0008] According to the invention, at least one web of material has one or more reference points with which the transverse position of the respective web of material, 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 of material runs laterally, i.e. transversely to the transport direction, i.e. its transport direction is not parallel to the packaging machine, in particular its frame and / or its chain run, or whether the transport direction runs parallel but, for example, the supply roll of the web of material 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 of material has changed. Webs of material, in particular webs of low quality, exhibit deviations from their parallelism relative to the transport direction of the web.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. Preferred reference points are also printed marks, which are preferably applied and / or embedded in the web at regular intervals. Furthermore, a print, such as a logo, on the web can serve as a reference point.

[0010] A reference point within the meaning of the invention can have any shape and size. Preferably, the reference points are repeated at regular intervals.

[0011] Based on this detection of the position of the reference point, the position of the web is changed, particularly upstream of the detection point of the reference point transversely to the transport direction of the web, if the just determined position of the reference point is outside a specified range. The change in the transverse position of the web preferably occurs upstream of the location where the position of the reference point is determined, relative to the transport direction of the web.

[0012] The position of the web of material can be changed transversely to its transport direction in any way familiar to a person 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 for axial movement 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 of material. However, to change the position of the web of material, the supply roll can be provided so as to be rotatable about at least one axis, for example a vertical and / or horizontal axis.

[0013] Alternatively or additionally, the material web can at least partially wrap around at least one, preferably several, rollers downstream of the supply roll. This roller(s) is / are preferably located between the supply roll and the detection point of the reference point. To change the position of the material web, this roller(s) is / are provided so that it can rotate about an axis, in particular a vertical axis.

[0014] The reference point is preferably detected by a sensor. The sensor is preferably an optical or ultrasonic sensor or a tactile sensor, which is preferably stationary, particularly with regard to its orientation transverse to the transport direction of the web. 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, wherein the wave reflected by the web has a different wavelength than the emitted wave, and the degree of the wavelength change is a measure of the change in position of the web (Doppler effect). The sensor preferably detects deviations of the reference point in two directions, for example to the right and to the left transverse to the transport direction of the web. Its exact position transverse to the transport direction can preferably be input into a control / regulation system.Alternatively or additionally, its distance from a reference point of the packaging machine, for example, its center axis in the longitudinal direction, the frame of the packaging machine, and / or the position of one or both chain strands, can be entered. However, the sensor can also be calibrated to a specific position of the reference point and then detect deviations from this position in two directions without specifying its exact position.

[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 directly adjacent to the film roll, particularly when the roll has its maximum diameter. According to another preferred embodiment, the sensor is located in the inlet area of ​​the chain strand, i.e., where the chain grippers clamp the edge of the web of material. According to a further preferred embodiment, the sensor is located between the supply roll and the inlet area of ​​the chain strand.Furthermore, a combination of at least two sensors is preferably arranged at preferably different positions between the supply roll and the inlet area of ​​the chain strand, for example in order to determine positional deviations at different points and, for example, to detect trends in the course and / or effects of the changes in the position therefrom and then to correct the changes in the position. Furthermore, a sensor is preferably provided upstream of the sealing station, preferably immediately upstream of the sealing station, in order to detect the position of the upper web of material relative to the position of the lower web of material, so that the control system can intervene in the event of significant deviations, for example in order to align a printed image and / or a deep-drawn shape on the upper web of material with the position of the packaged goods and / or the packaging troughs on / in the lower web of material in the transverse direction.The expert understands that the position of the upper fabric web can also be recorded with more than one sensor and, if necessary, tendencies (trends) for the course behavior.

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

[0017] Preferably, the edge of the web, 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 are detected as the reference point.

[0018] Preferably, the control system measures the distance between the reference point and the center of the packaging machine, the frame of the packaging machine, and / or the chain strand. These values ​​can then be used to control the position of the web of material transverse 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 method according to the invention corrects the course of the web.

[0021] Furthermore, the method according to the invention 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 errors in the production of the web can be compensated for using the method according to the invention in such a way that there is no interruption to the packaging production process.

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

[0023] Based on the position of at least one reference point, the transverse position of the web roll can also be recorded and corrected if necessary. This function is particularly interesting when changing rolls. The sensor records the position, for example of one of the first reference points. The transverse position of the web roll is then corrected if necessary. 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 and the start of the web has been brought into its takeover position, for example by attaching it to the end of the previous web, and the new web has been placed under a minimum longitudinal tension and, if necessary, the actual position of the web roll has been recorded, after which the position of the web roll is corrected if necessary, preferably until the displayed target position is at least approximately reached or exceeded.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 a visual 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 based on the target position of the web roll, preferably centered with regard to the adjustment travel of the actuators, so that the usually limited adjustment travel of the actuators permits axial adjustment of the axis of rotation or the supply roll relative to the axis of rotation without having to exceed the limits of the adjustment travel.

[0024] A trend analysis is preferably carried out using the data recorded by the sensor. This preferably determines whether there is a preferred direction in which the pattern occurs. This analysis can then be used, for example, to make a change to the packaging machine. The analysis can also be used to investigate whether the pattern is batch-dependent and, if so, to determine with the respective manufacturer what causes the pattern and how this error can be remedied. A pattern can be due, for example, to a non-consistent thickness of the web and / or that the web was not stretched evenly. However, the trend analysis can also indicate fluctuations in the width of the web and / or that the edges of the web are not parallel to the direction of transport, but for example curved, in particular sine or cosine-shaped.

[0025] The data collected by the sensor(s) can also be used to generate an error message and / or stop the machine. For example, an error message or machine stop can occur if: the lateral adjustment range of the control has been reached or exceeded, a recorded trend cannot be stopped or reversed, if the sensors detect that a web of the wrong width has been applied, if the recorded data shows that the web is of inferior quality and / or if the recorded data shows that the web has not been correctly mounted on the packaging machine shaft, 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 parallelism to the transport direction can be improved.

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

[0028] In the following, the inventions are described on the basis of Figures 1 to 4These explanations are merely exemplary and do not limit the general concept of the invention. The explanations apply equally to all subject matter 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 from Figure 2 Figure 4 shows the web unwinding of a packaging machine.

[0029] Figure 1shows the packaging machine 1 according to the invention, which here has a thermoforming station 2, a filling station 7 and a sealing station 15. A bottom web 8, here a plastic web 8, is drawn off from a supply roll 22 and transported in cycles along the packaging machine from right to left in its transport direction 40. In one cycle, the bottom web 8 is transported further by one format length / feed length. For this purpose, the packaging machine has two transport means 24 (in Figure 1not shown), in the present case two endless chains, two chain strands, which are arranged to the right and left of the lower fabric web 8. At least one gearwheel 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 gearwheels is driven. The gearwheels in the input area and / or in the output area can be connected to one another, preferably by a rigid shaft. Each transport means has a plurality of clamping means 42 (cf. Figure 3) which clamp the lower web 8 in the inlet area 19 and transfer the movement of the transport means to the lower web 8. In the outlet area of ​​the packaging machine, the clamped connection between the transport means and the lower web 8 is released again. Downstream of the inlet area 19, a heating means 13 can be provided which heats the web 8, in particular when the web is stationary. In the optionally present deep-drawing station 2, which has an upper tool 3 and a lower tool 4 which has the shape of the packaging tray to be produced, the packaging trays 6 are formed into the optionally heated web 8. The lower tool 4 is arranged on a lifting table 5 which, as symbolized by the double arrow, is vertically adjustable. Before each web feed, the lower tool 4 is lowered and then raised again.As the packaging machine continues, the packaging troughs or a flat lower web are then filled / loaded with the packaging material 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 upper web 14 is firmly sealed to the lower web 8. This transfers the movement of the lower web 8 to the upper web 14. In the sealing station, the upper tool and / or the lower tool are also lowered or raised before and after each web transport. The upper film 14 can also be guided in transport means or transported by transport chains, whereby these transport means then extend only in front of the sealing station and, if necessary, downstream. Otherwise, the statements made regarding the transport means for the lower film apply.The upper film can also be heated with a heating medium and deep-drawn. For sealing, a heatable sealing frame is provided as the lower tool 11, for example, which 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 upper and lower 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, in this case a rotary dancer, can be provided between the supply roll 21 and the sealing tool to keep the web 14 at as constant a tension as possible. The person skilled in the art will understand that several upper webs / intermediate layers can be present, for example in the case of a multi-layer pack or a pack with several upper webs.Preferably, a dancer is then provided along the length of each upper film. Those skilled in the art will further understand that a dancer can also preferably be provided in the region of the lower film, preferably downstream of the supply roll 22. The dancer is preferably a linear dancer. Before and / or during the sealing of the upper film to the lower film, a gas exchange preferably takes place in each packaging tray. For this purpose, the air present in the packaging tray is first partially sucked out and then replaced with a replacement gas. For this purpose, holes are made in the lower product web in the area of ​​the transport chains in the lower film in the area of ​​each format, through which the air between the product webs 8, 14 is sucked out and the replacement gas is then blown in. Further along the packaging machine, the finished packages are separated, which in the present 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 using 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 length of advance of the respective web of fabric is unrolled from the roll without the tensile force of the two transport means, the transport chains, and / or the tensile force of the lower web of fabric being significantly transferred to the upper web of fabric. As a result, the respective web of fabric is subjected to only a comparatively low tension and is thus pre-stretched at most slightly, producing fewer wrinkles.

[0031] With the method according to the invention, even comparatively thin webs and / or webs with a low quality, in particular with regard to homogeneity in terms of shape and / or composition, can be processed.

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

[0033] Preferably, the dancer is equipped with a motion sensor, such as a rotary encoder or a linear encoder, which can be used to determine which stored web length the dancer's movement corresponds to. 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 lower and upper fabric webs. Preferably, the supply roll of the lower fabric web and / or the upper fabric web is driven by a motor such that the unwinding of the respective fabric web is carried out by a motor drive in such a way that the respective fabric web is subjected to only insignificant tension.

[0035] Figures 2 and 3 show a first embodiment of the method according to the invention, wherein in Figure 3 a detail from Figure 2is shown. A web of material 8, 14 is unwound from a roll 20, 22 and transported in a transport direction 40. For various reasons, a path 46 of the web of material transverse to its transport direction 40 can occur, which is compensated for by the method according to the invention. For this purpose, the packaging machine has a sensor 39, in particular a stationary sensor fixed to the machine frame, 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 running and / or whether the reference point is 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 center 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 strand 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 transversely to its transport direction. This can be done, for example, using a device that is based on . Figure 4 is described in more detail. The correction preferably takes place upstream of the sensor 39.

[0036] Figure 4 shows a further embodiment of the packaging machine, essentially referring to the embodiments according to Figure 1can be referred to. The supply roll 21, 22 is mounted on a shaft 23, preferably in a rotationally fixed and / or axially non-displaceable manner. The shaft 23 rotates in the direction indicated by the arrow 40 as the lower and / or upper web of fabric 8, 14 unwinds. The shaft 23 is preferably mounted in the region of its two ends by means of a bearing 31 so as to be rotatable and, if necessary, also longitudinally displaceable. A bearing 31 can be provided, for example, on the housing of the web unwinder or the packaging machine. For longitudinal displacement, the bearings 31 can be designed as plain bearings. The shaft 23 is preferably driven in rotation by means of a motor 25. A coupling 26, for example a sliding coupling or a gear, preferably a sliding gear, 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 unwinder is mounted is provided for longitudinal displacement, as symbolized by the arrow 37 and / or transversely 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 provided is provided for longitudinal displacement, for example along a guide 32. The movement 37 is effected, for example, by an adjusting drive 35, which moves at least the shaft 23 along its central axis, but preferably also the frame 29. Those skilled in the art will understand that the drive motor 25 can also be moved during the longitudinal displacement, but this does not have to be the case. The bearings 32-34 are preferably arranged on a base frame 28, in particular a stationary one.

[0037] The packaging machine according to the invention preferably 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] During start-up or during a supply roll change, the sensor signal can also be used to correct the axial position of the roll on the shaft 23. List of reference symbols:

[0039] 1Packaging machine 2Forming station, thermoforming station 3Upper tool of the thermoforming station 4Lower tool of the thermoforming station 5Lifting table, support of a tool of the sealing, thermoforming station and / or the cutting device 6Packaging trough 7Filling station 8Product web, lower web, product web 9Lifting device 10Drive 11Lower tool of the sealing station 12Upper tool of the sealing station 13Heating medium 14Upper web, lidding film, product web 15Sealing station 16Packaged goods 17Length cutter 18Cross cutter 19Inlet area 20Dancer 21Supply roll of the upper web 22Supply roll of the lower web 23Supply roll shaft 24Chain 25Motor, torque motor 26Coupling, sliding coupling 27Motor shaft 28Base frame, packaging machine 29Support, movable frame 30Door, Bearing housing, frame 31Bearing, plain bearing 32Guide, guide rod 33Bearing, plain bearing 34Bearing block, bearing housing 35Adjustment drive, motor, gear motor, spindle motor, servo motor 36Spindle, shaft, adjustment device,Sliding means 37Adjustment direction, sliding direction 38Reference point, web edge, material web edge, material web edge 39Sensor, web edge detection means 40Transport direction, material web running direction, web running direction 41Center axis of the packaging machine 42Clamping means, gripper 43Distance material web edge to packaging machine center 44Distance material web edge to chain 45Distance material web edge to base frame 46Line of the material web,

Claims

1. A method for controlling the position of a lower and / or upper web of fabric (8, 14) on a packaging machine, wherein the lower web of fabric (8) is unrolled from a supply roll (22) and transported intermittently or continuously along the packaging machine, and in the process, if appropriate, packaging troughs (6) are formed into the lower web of fabric (8) in a forming station (2), and the lower web of fabric, preferably the packaging troughs, are then covered with a packaging item (16), wherein subsequently, in a sealing station (15), an upper web of fabric (14) is joined to the lower web of fabric (8), wherein the lower and upper webs (8, 14) are each unrolled from a supply roll (21, 22), characterized in that the position of a reference point (38) on the upper web (14) relative to a preferably stationary component of the packaging machine is detected and, based on this detection, the position of the upper web (8, 14) transversely to its transport direction is changed if necessary.

2. Method according to claim 1, characterized in that the reference point (38) is detected by a sensor (39).

3. Method according to claim 1 or 2, characterized in that the edge of the web, a print mark and / or print image, in particular the edge of a print image, is detected as a reference point (38).

4. Method according to one of claims 1 - 3, characterized in that the distance between the reference point and the center (41) of the packaging machine, the frame (28) of the packaging machine and / or the chain strand (24) is determined.

5. Method according to one of claims 2 - 4, characterized in that the sensor (39) is provided downstream of the web roll (14) with respect to the web transport direction.

6. Method according to one of claims 2 - 5, characterized in thata sensor is provided upstream of the sealing station, preferably immediately upstream of the sealing station, to detect the position of the upper fabric web relative to the position of the lower fabric web, so that the control can intervene in the event of significant deviations.

7. Method according to claim 6, characterized in that a printed image and / or a deep-drawn shape on the upper web is aligned in the transverse direction to the position of the packaged goods and / or the packaging troughs on / in the lower web.

8. Method according to claim 6 or 7, characterized in that the position of the upper fabric web is recorded with more than one sensor and / or tendencies (trends) for the course behavior.

9. Method according to one of the preceding claims, characterized in that the sensor is adjustable in height and / or length.

10. Method according to one of the preceding claims, characterized in that a path of the web is corrected.

11. Method according to one of the preceding claims, characterized in that Deviations in the nominal width and / or deviations in the parallelism of the edge of the web relative to its transport direction are compensated.

12. Method according to one of the preceding claims, characterized in that Inhomogeneities in the material path are compensated.

13. Method according to one of the preceding claims, characterized in that the position of the web roll is recorded and corrected if necessary.

14. Method according to one of the preceding claims, characterized in that the target position and / or actual position of the web roll is displayed and the position of the web roll is corrected by axial displacement on its axis of rotation using the display.

15. Method according to one of the preceding claims, characterized in thatthe rotation axis is brought into a position, preferably centered with respect to the adjustment paths of the actuators, based on the desired position of the web roll, such that the usually limited adjustment paths of the actuators allow axial adjustment of the rotation axis or the supply roll relative to the rotation axis without the limits of the adjustment paths having to be exceeded.

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