Method for controlling the position of a material web edge

Abstract

A packaging machine and a method for controlling the position of a lower and/or upper material web on a packaging machine. A lower material web is unwound from a supply roll and transported intermittently or continuously along the packaging machine. Packaging recesses are optionally formed in the lower material web in a forming station, and the lower material web, preferably the packaging recesses, are then filled with products to be packaged. An upper material web is then sealed to the lower material web in a sealing station, the lower and upper material web each being unwound from a supply roll.

Claims

1. A method for controlling a position of a lower material web and/or a upper material web on a packaging machine, wherein the lower material web is unwound from a first supply roll and transported intermittently or continuously along the packaging machine, packaging recesses are optionally formed in the lower material web in a forming station, and the lower material web, or the packaging recesses, are then covered with products to be packaged, an upper material web is then sealed to the lower material web in a sealing station, the upper material web being unwound from a second supply roll, wherein a position of a reference point on the lower material web and/or the upper material web relative to a stationary component of the packaging machine is detected and, on a basis of the detection, the position of the lower material web and/or the upper material web transverse to a transport direction is changed if necessary.

2. The method as claimed in claim 1, wherein the reference point is detected by a sensor.

3. The method as claimed in claim 1, wherein a material web edge, a printed mark, and/or a printed image is detected as the reference point.

4. The method as claimed in claim 1, wherein a distance between the reference point and a center of the packaging machine, a frame of the packaging machine, and/or a chain run is determined.

5. The method as claimed in claim 1, wherein a sensor is provided downstream of the upper material web and/or the lower material web relative to a transport direction of the upper material web and/or the lower material web.

6. The method as claimed in claim 5, wherein the sensor detects the reference point at an entry to a chain run.

7. The method as claimed in claim 1, wherein the sensor is vertically and/or longitudinally adjustable.

8. The method as claimed in claim 1, wherein a run-out of the material web is corrected.

9. The method as claimed in claim 1, wherein deviations of a nominal width and/or deviations of parallelism of an edge of the material web relative to a transport direction are compensated.

10. The method as claimed in claim 1, wherein inhomogeneities in the material web are equalized.

11. The method as claimed in claim 1, wherein the position of the upper material web relative to the position of the lower material web is changed.

12. The method as claimed in claim 1, wherein the position of the material web roll is detected and corrected if necessary.

13. The method as claimed in claim 1, wherein a target position and/or an actual position of the material web roll is displayed, and the position of the material web roll is corrected by axial displacement on its axis of rotation by using a display.

14. The method as claimed in claim 1, wherein using the target position of the material web roll, an axis of rotation is moved into a centered position, with regard to adjustment travels of actuating drives, such that usually limited adjustment travels of the actuating drives that are provided permit an axial displacement of the axis of rotation or the supply roll relative to the axis of rotation without the limits of the adjustment travels having to be exceeded.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The inventions will be explained below by using FIGS. 1 to 4. These explanations are merely exemplary and do not restrict the general idea of the invention. The explanations apply equally to all the subjects of the present invention.

[0034] FIG. 1 shows the packaging machine according to the invention.

[0035] FIG. 2 shows a first embodiment of the method according to the invention.

[0036] FIG. 3 shows the detail Z from FIG. 2.

[0037] FIG. 4 shows the material web unwind of a packaging machine.

DETAILED DESCRIPTION

[0038] FIG. 1 shows the packaging machine 1 according to the invention, which here has a deep-drawing station 2, a filling station 7 and a sealing station 15. A lower material web 8, here a plastic material web 8, is drawn off a supply roll 22 and transported cyclically from right to left in its transport direction 40 along the packaging machine. During one cycle, the lower material web 8 is transported onward by a format length/feed length. For this purpose, the packaging machine has two transport means 24 (not shown in FIG. 1); in the present case respectively two endless chains, two chain runs, which are arranged on the right and left of the lower material web 8. Both at the start and at the end of the packaging machine, at least one gearwheel, around which the respective chain is deflected, is respectively provided for each chain. At least one of these gear wheels is driven. The gear wheels in the entry region and/or in the exit region can be connected to each other, preferably by a rigid shaft. Each transport means has a multiplicity of clamping means 42 (cf. FIG. 3), which grip the lower material web 8 in the entry region 19 in a clamping manner and transmit the movement of the transport means to the lower material web 8. In the exit region of the packaging machine, the clamping connection between the transport means and the lower material web 8 is released again. Downstream of the entry region 19, a heating means 13 can be provided, which heats the material web 8, in particular when the latter is at a standstill. In the deep-drawing station 2 which may be present and which has an upper tool 3 and a lower tool 4 which has the shape of the packaging recess to be produced, the packaging recesses 6 are formed in the possibly heated material 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 material web feed, the lower tool 4 is lowered and then raised again. In the further course of the packaging machine, the packaging recesses or a flat lower material web is/are filled/covered with the product to be packaged 16 in the filling station 7. In the sealing station 15 which then follows and which likewise comprises an upper tool 12 and a vertically adjustable lower tool 11, an upper material web 14 is fixed integrally to the lower material web 8 by sealing. As a result, the movement of the lower material web 8 is transmitted to the upper material web 14. In the sealing station, too, the upper tool and/or the lower tool are lowered and raised before and after each material web transport. The upper film 14 can also be guided in transport means or transported by transport chains, these transport means then extending only before the sealing station and possibly downstream. Otherwise, the explanations given in relation to the transport means of the lower film apply. The upper film can also be heated by a heating means and deep-drawn. For the sealing, a heatable sealing frame, for example, is provided as the lower tool 11, which has an opening for each packaging recess, into which the packaging recess dips during the sealing, i.e. during the upward movement of the lower sealing tool. For the sealing, the upper and the lower material web are pressed together between the upper and lower tool 12, 11 and are connected under the influence of heat and pressure. After the sealing, the tools 11, 12 are moved apart vertically again. Between the supply roll 21 and the sealing tool, a dancer 20, here a rotating dancer, can be provided, which keeps the material web 14 as far as possible at a constant tension. Those skilled in the art will understand that a plurality of upper material web/intermediate layers can be present, for example in a multilayer package or a package having multiple upper material webs. Preferably, a dancer is then provided in the run of each upper film. Those skilled in the art will also understand that a dancer can preferably be provided in the region of the lower film as well, 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 is preferably carried out in each packaging recess. For this purpose, the air present in the packaging recess is firstly partly extracted and then replaced by a replacement gas. For this purpose, in the region of each format in the lower film in the region of the transport chains, holes are introduced into the lower material web, through which the air between the material webs 8, 14 is extracted and the replacement gas is then blown in. In the further course of the packaging machine, the finished packages are separated, which in the present case is carried out by the cross-cutter 18 and the longitudinal cutter 17. In the present case, the cross-cutter 18 can likewise be raised and lowered by a lifting device 9.

[0039] Preferably, at least one supply roll 21, 22 is driven by a motor, in particular a torque motor, such that the length of the respectively needed feed of the respective material web is unwound from the roll without the tensile force of the two transport means, the transport chains and/or of the tensile force of the lower material web being transmitted noticeably to the upper material web. As a result, the respective material web is subjected to only a comparatively low tension and is thus slightly pre-stretched, if need be, and develops fewer creases.

[0040] With the method according to the invention, even comparatively thin material webs and/or material webs with a low quality as regards in particular homogeneity in relation to shape and/or composition can be processed.

[0041] Preferably, the rotation of the motor that drives the supply roll 21, 22 is controlled/regulated by a computer means, which can be part of the packaging machine or part of a line control system. In particular, the rotational speed of the supply roll can be controlled such that the unwound material web length corresponds to the feed, and/or the speed profiles of the unwind of the material web and/or of the feed of the transport means, in particular the transport chains, is at least substantially identical. The respective actual diameter or the respective actual weight of the supply roll is taken into account.

[0042] Preferably, the dancer is provided with a movement transmitter, for example a rotary encoder or a linear encoder, with which it is possible to determine that stored material web length which corresponds to the movement of the dancer. This information can be used, for example, to determine the diameter of the supply roll.

[0043] Preferably, a dancer is provided in the region of the lower and the upper material web. Preferably, the supply roll of the lower material web and/or the upper material web is driven by a motor such that the respective material web is unwound by a motor drive such that the respective material web is insubstantially tensioned if need be.

[0044] FIGS. 2 and 3 show a first embodiment of the method according to the invention, a detail from FIG. 2 being illustrated in FIG. 3. A material web 8, 14 is unwound from a roll 20, 22 and transported in a transport direction 40. For various reasons, it is possible for a run-out 46 of the material web transverse to its transport direction 40 to occur, which is controlled away in a compensatory manner by the method according to the invention. For this purpose, the packaging machine has an in particular stationary sensor 39 fixed to the machine frame, which detects the position of one or more reference points. By using this measurement, a control system can determine whether the material web is running out and/or whether the reference point is located in an acceptable range relative to a component of the packaging machine. The reference point is, for example, the material web edge 38, a printed mark or a printed image. By way of example, the distance 43 between the reference mark and the mid-axis 41 of the packaging machine is determined and/or the distance 44 between the reference mark, here the edge of the material web, and the chain run and/or the grippers 42 of the latter is determined. Alternatively or additionally, the distance of the reference mark from the machine frame 28 can also be determined. By using the signal from this sensor 39, a control system corrects the position of the film web 8, 14 transverse to its transport direction. This can be done, for example, by using a device which is described in more detail by using FIG. 4. The correction is preferably carried out upstream of the sensor 39.

[0045] FIG. 4 shows a further embodiment of the packaging machine, wherein reference can substantially be made to the explanations according to FIG. 1. The supply roll 21, 22 is mounted on a shaft 23, preferably co-rotationally and/or not axially displaceably. As the lower and/or upper material web 8, 14 is unwound in the direction indicated by the arrow 40, the shaft 23 rotates. The shaft 23 is preferably rotatably and possibly also longitudinally displaceably mounted in the region of its two ends by means of a bearing 31. A bearing 31 can be provided, for example, on the housing of the material web unwind or on the packaging machine. For a longitudinal displacement, the bearings 31 can be implemented as sliding bearings. The shaft 23 is preferably driven in rotation by means of a motor 25. Between the motor 25 and the shaft 23, a coupling 26, for example a disk clutch or a gear mechanism, preferably a disk gear mechanism, can be provided. The invention provides for the shaft 23 on its own and/or the frame 29 on which the shaft 23 of the material web unwind is supported, to be longitudinally displaceable, which is symbolized by the arrow 37, and/or transverse to the transport direction 40 of the material web. For the purpose, for example, the frame 29 on which the shaft 23 and the motor 25 are provided is provided to be longitudinally displaceable, for example along a guide 32. The movement 37 is effected by an adjustment drive 35, for example, which moves at least the shaft 23 along its mid-axis but preferably additionally 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 does not have to be. The mounting 32-34 is preferably arranged on an in particular stationary base frame 28.

[0046] Preferably, the packaging machine according to the invention has a sensor 39, which is preferably a web edge detection means. Said web edge detection means 39 detects the position of the web edge, for example relative to the frame of the packaging machine or another preferably stationary location. Should the web edge be located on the other side of a desired limit, the adjustment drive 35 is preferably activated, then moving the shaft 23 or the frame 29 in the direction symbolized by the arrows 37 until the material web is once more located within the desired limit.

[0047] During start-up or during a supply roll change, the signal from the sensor can also be used to correct the axial position of the roll on the shaft 23.

LIST OF DESIGNATIONS

[0048] 1 Packaging machine [0049] 2 Forming station, deep-drawing station [0050] 3 Upper tool of the deep-drawing station [0051] 4 Lower tool of the deep-drawing station [0052] 4 Lifting table, carrier of a tool of the sealing, deep-drawing station and/or the cutting device [0053] 6 Packaging recess [0054] 7 Filling station [0055] 8 Material web, lower material web, material web [0056] 9 Lifting device [0057] 10 Drive [0058] 11 Lower tool of the sealing station [0059] 12 Upper tool of the sealing station [0060] 13 Heating means [0061] 14 Upper material web, covering film, material web [0062] 15 Sealing station [0063] 16 Product to be packaged [0064] 17 Longitudinal cutter [0065] 18 Cross-cutter [0066] 19 Entry region [0067] 20 Dancer [0068] 21 Supply roll of the upper material web [0069] 22 Supply roll of the lower material web [0070] 23 Shaft of the supply roll [0071] 24 Chain [0072] 25 Motor, torque motor [0073] 26 Coupling, disk clutch [0074] 27 Motor shaft [0075] 28 Base frame, packaging machine [0076] 29 Support, displaceable frame [0077] 30 Door, bearing housing, frame [0078] 31 Bearing, sliding bearing [0079] 32 Guide, guide rod [0080] 33 Bearing, sliding bearing [0081] 34 Bearing block, bearing housing [0082] 35 Adjustment drive, motor, geared motor, spindle motor, servo motor [0083] 36 Spindle, shaft, adjustment means, displacement means [0084] 37 Adjustment direction, displacement direction [0085] 38 Reference point, web edge, material web edge, material web edge [0086] 39 Sensor, web edge detection means [0087] 40 Transport direction, material web running direction, web running direction [0088] 41 Mid-axis of the packaging machine [0089] 42 Clamping means, gripper [0090] 43 Distance between the material web edge and the packaging machine center [0091] 44 Distance between the material web edge and the chain [0092] 45 Distance between the material web edge and the base frame [0093] 46 Run-out of the material web