Weakening Device and Method for Weakening Packaging Materials

Abstract

Described is a weakening device for weakening packaging materials having at least one laser unit comprising a laser having a laser beam and at least one transport device for transport of the packaging material relative to the laser unit. The laser unit has at least one focusing optics for focusing the laser beam on the packaging material transported relative to the laser. In order to be able to inscribe both straight lines of weakness and shapes included from lines, it is provided that the laser unit has at least one scanner for adjusting the laser beam at least in one direction transversely to the transport direction for inscribing predetermined shapes into the packaging material transported past the laser, and that a beam switch is provided in the path of the laser beam for transmitting the beam to the focusing optics in a liner position or to the scanner.

Claims

1. A weakening device for weakening packaging materials having at least one laser unit comprising a laser for irradiating and partially removing the packaging material with a laser beam and having at least one transport device for transport of the packaging material relative to the at least one laser unit, wherein the at least one laser unit has at least one focusing optics for focusing the laser beam on the packaging material transported relative to the laser by the transport device, wherein the laser unit has at least one scanner for adjusting the laser beam in at least one direction transverse to a transport direction for inscribing predetermined shapes into the packaging material transported past the laser and in that a beam switch is provided in a beam path of the laser beam in the at least one laser unit, which transmits the laser beam optionally to the at least one focusing optics in a linear position or to the at least one scanner in a scanner position.

2. The weakening device according to claim 1, wherein the at least one scanner has at least one mirror adjustably arranged in the beam path for adjusting the laser beam reflected by the at least one mirror.

3. The weakening device according to claim 1, wherein the beam switch is configured to be adjustable at least from a liner position for directing the laser beam to the at least one focusing optics into a scanner position for directing the laser beam to the at least one scanner and back.

4. The weakening device according to claim 3, wherein the beam switch abuts on a stop in the liner position and/or in the scanner position.

5. The weakening device according to claim 3, wherein an electric drive or pneumatic drive is associated with the beam switch for adjusting the beam switch from the liner position to the scanner position and/or back.

6. The weakening device according to claim 1, wherein an extractor hood for extracting the packaging material removed by the laser beam is provided in the beam path and adjacent to the packaging material, and in that the extractor hood has an open housing section or a housing section transparent to the laser beam for the laser beam to enter the extractor hood.

7. A weakening device according to claim 1, wherein a second focusing optics is provided in the beam path passing through the scanner, and in that the second focusing optics associated with the scanner is configured for focussing the laser beam perpendicular to the packaging material in accordance with the deflection of the laser beam by the scanner in the transport direction of the packaging material and/or in a direction perpendicular to the transport direction and parallel to the packing material.

8. The weakening device according to claim 1, wherein at least the laser, the beam switch, the at least one focusing optics or the scanner of the at least one laser unit are mounted stationary relative to each other on a holding device of the laser unit and that the holding device is mounted adjustably in at least one direction.

9. The weakening device according to claim 1, wherein at least one laser unit is provided and the at least one laser unit is provided at least partially in a direction perpendicular to the transport direction of the packaging material and parallel to the packaging material adjacent to one another and/or behind one another at least partially in the transport direction of the packaging material.

10. A weakening device according to claim 1, wherein a sensor is provided for detecting control marks on the packaging material, in particular in the form of printed marks and/or embossed marks, and in that, preferably, a control device is provided for controlling the scanner depending on the detection, in particular the time of detection, of the control marks by the sensor.

11. A method for weakening packaging materials, the method comprising the steps of: transporting the packaging material past at least one laser unit by a transport device; using the at least one laser unit to generate a laser beam that irradiates the packaging material and partially removes it; and directing the at least one laser beam by a beam switch to a focusing optics in a liner position, for focusing the laser beam towards the packaging material, or to a scanner in a scanner position, for adjusting the laser beam at least in a direction transverse to a transport direction, for inscribing predetermined shapes on the packaging material.

12. The method according to claim 11, further comprising: impinging the energy of the laser beam on the packaging material at least temporarily varies, in particular pulses, such that different amounts of packaging material are removed at different points of the packaging material.

13. The method according to claim 11, further comprising: inscribing a line of weakness into the packing material parallel to the transport direction of the packaging material by a laser beam passing the beam switch in the liner position; and/or inscribing a line of weakness into the packaging material extending at least partially in a direction perpendicular to the transport direction and parallel to the packaging material by a laser beam passing through the beam switch in the scanner position.

14. The method according to claim 11, further comprising: adjusting the laser beam passing through the scanner in a first direction during the inscribing of a shape on the packaging material; and adjusting the laser beam passing through the scanner in a second direction during the inscribing of a shape on the packaging material.

15. A method according to claim 11, further comprising: inscribing similar shapes into the packaging material in the form of lines of weakness, said shapes being spaced apart, and these are inscribed by means of a laser beam passing through beam switch in the scanner position; and/or inscribing a straight line of weakness into the packaging material, said line of weakness extending in particular parallel to the transport direction of the packaging material, and interrupted in sections, and this is inscribed by means of a laser beam passing through the beam switch in the liner position.

16. The method according to claim 11, further comprising: initiating the inscribing of a line of weakness, a part of a line of weakness and/or a shape by identifying at least one control mark by at least one sensor.

17. The method according to claim 11, further comprising: focusing a laser beam passing through a beam switch in the scanner position by means of a focusing optics in accordance with the deflection of the laser beam in the transport direction of the packaging material and/or in accordance with the deflection of the laser beam in a direction perpendicular to the transport direction of the packaging material and parallel to the packaging material.

18. The weakening device of claim 2, wherein the at least one scanner has two mirrors which are adjustable in at least substantially vertical directions relative to one another.

19. The weakening device of claim 2, wherein the at least one mirror is configured to adjust the laser beam in the transport direction of the packaging material and at least one other mirror is configured to adjust the laser beam in a direction perpendicular to the transport direction and parallel to the packaging material.

20. The weakening device of claim 5, wherein the electric drive or pneumatic drive is a double piston drive.

Description

[0038] The invention will subsequently be explained in more detail with reference to a drawing depicting only exemplary embodiments. The following are shown in the drawing:

[0039] FIG. 1A-C packaging blanks cut from packaging material webs produced with the weakening device according to the present invention and the method according to the present invention for forming a package, in plan view,

[0040] FIG. 2 a packaging material web used by the weakening device according to the invention and in the method according to the invention,

[0041] FIG. 3 an weakening device according to the invention while carrying out the method according to the invention with a packaging material web according to FIG. 2 in a schematic side view,

[0042] FIG. 4A-B a detail of the weakening device from FIG. 3 and an alternative weakening device in a schematic side view,

[0043] FIG. 5 a laser unit of the weakening device from FIG. 3 together with beam paths of the laser in a purely schematic representation,

[0044] FIG. 6 a purely schematic representation of the inscribing of a line of weakness into a packaging material with the weakening device from FIG. 3 and the method according to the present invention and

[0045] FIG. 7A-B the beam switch of the weakening device from FIG. 3 in a perspective detail view.

[0046] In FIGS. 1A-C, packaging blanks 1, 2, 3 for producing different packaging are shown. The packaging materials 4 of the packaging blanks 1, 2, 3 are designed as packaging laminates and accordingly comprise several layers of different materials. The illustrated and in this respect preferred packaging material 4 is one with outer layers made from a thermoplastic resin, in particular an olefin, particularly preferably polyethylene (PE), but if necessary also polypropylene (PP). The side of the packaging material 4 pointing outwards in the subsequent packaging and shown in FIGS. 1A-C is additionally printed. For the sake of better clarity, the print is not shown, since the process of printing packaging materials is well known. Only at the lower left, a control mark 5 in the form of an imprinted printed mark is schematically illustrated, which defines the relationship between a specific point on the packaging material 4 of a packaging material web and a specific point of the subsequent packaging blank 1, 2, 3. In particular, the control mark 5 also determines at which points the packaging material web is cut in order to produce the packaging blanks 1, 2, 3. This ensures that the printed decoration is always provided in the designated place and in the intended manner on the packaging.

[0047] The illustrated and in this respect preferred packaging blanks 1, 2, 3 also have what are known as score lines 6 or pre-fold lines, on which the packaging material 4 or the packaging blank 1, 2, 3 is folded to form the packaging. This simplifies the formation of the packaging and ensures that the packaging is produced with the desired quality and shape. Frequently, but not necessarily, the layers of the packaging material laminate are first laminated to form a packaging material web and rolled up into packaging material rolls. Subsequently, the packaging material web is unrolled again to be printed. The printed packaging material web is frequently rolled up again into a packaging material roll. After the packaging material web is again unrolled from the packaging material roll, the packaging material web is provided with lines of weakness 7 and then with the score lines 6 or pre-fold lines. Subsequently, the packaging material web is cut longitudinally and transversely to form the individual packaging blanks 1, 2, 3. Typically, not only the subsequent packaging blanks 1, 2, 3 are provided behind one another in the longitudinal direction on a packaging material web. Rather, several rows of subsequent packaging blanks 1,2,3 are provided adjacent to each other on the packaging material web. The number of rows can be chosen arbitrarily. However, two, four or six adjacent rows have proved to be particularly expedient.

[0048] The packaging blanks 1, 2, 3 shown in FIGS. 1A-C differ with regard to the shape of the lines of weakness 7 introduced into the respective packaging material 4. The lines of weakness 7 are lines along which the layer thickness of the packaging material 4 is at least partially reduced, as a result of material removal. The removal of material is brought about by inscribing the packaging material 4 with a laser beam 8, wherein the packaging material 4 absorbs so much energy that certain parts of the packaging material are vaporised and, if necessary, other parts of the packaging material are blast off by vaporisation. In the packaging laminates shown in FIGS. 1A-C, the lines of weakness 7 are shown as dashed lines and also inscribed in dashed lines in the packaging material. Short weakened sections of the lines of weakness 7 are recurrently followed by short unweakened or hardly weakened sections and vice versa.

[0049] In FIG. 1A, the line of weakness 7 is provided in a straight line and continuously over the entire packaging blank 1. The line of weakness 7 is aligned parallel to the transport direction of the packaging material web along the laser beam 8. The present line of weakness 7 is a line of weakness 7, which forms what is referred to as a one-dimensional shape, even if the line of weakness 7 as a matter of course extends at least in sections in a direction perpendicular to the line of weakness 7 and parallel to the packaging material 4 as well as in a direction perpendicular to the line of weakness 7 and perpendicular to the packaging material 4. Nevertheless, the line of weakness 7 extends in a straight line along the packaging blank 1. Due to the straight line of weakness 7, the subsequent packaging can simply be torn open over the entire length at the top of the packaging in order, for example, to be able to pour out foodstuffs packaged therein.

[0050] On the other hand, the lines of weakness 7 of the packaging blanks 2, 3 illustrated in FIGS. 1B-C form a two-dimensional shape 9, 10. Namely, the lines of weakness 7 extend at least also in a direction perpendicular to the transport direction of the packaging material web and parallel to the packaging material 4. In the packaging blank 2 according to FIG. 1B, the line of weakness 7 forms a circle. The packaging material 4 can be pressed in along the line of weakness 7, for example through a spout provided above, in order to be able to pour out the foodstuff packaged in the packaging. If required, the shape 9 of the line of weakness 7 could be inscribed into the packaging material 4 in a form different from a circle and/or not closed.

[0051] The line of weakness 7 of the packaging blank 3 shown in FIG. 1C likewise forms a two-dimensional shape 10, namely an approximately V-shaped form adjacent to an edge of the packaging blank 3. This line of weakness 7 subsequent makes it possible to tear off a corner from the packaging in order to be able to pour out a packaged foodstuff, for example, through the opening in the packaging thus formed. Other lines of weakness 7 are also conceivable.

[0052] FIG. 2 shows a packaging material web 11 after the introduction of score lines 6 into the packaging material 4. In practice, the packaging material web 11 also has a printed decoration and the lines of weakness 7. The lines of weakness 7 and the decoration have been omitted for the sake of clarity, however, in FIG. 2. Only the control marks 5 in the form of imprinted printed marks are shown, which are separately printed on the illustrated packaging material web 11 for each of the subsequent packaging blanks 12. The transport direction T of the packaging material web 11 extends from right to left in the packaging material web 11 shown in FIG. 2. In the transport direction T four subsequent packaging blanks 12 are provided side by side. In other words, the packaging material web 11 can be cut in the longitudinal direction or in the transport direction T of the packaging material web 11 into four partial webs, along which a row 13 of subsequent packaging blanks 12 are respectively provided. Each of these partial webs can then be divided transversely to the partial web to form the individual packaging blanks 12.

[0053] FIG. 3 shows an weakening device 14 for introducing lines of weakness 7 into a packaging material web 11. The packaging material web 11, which has been printed but not yet provided with lines of weakness 7 or score lines 6, is unrolled from a packaging material roll 15 and transported past at least one sensor 16, which in the illustrated and in this respect preferred weakening device 14 is an optical sensor 16. The transport speed of the packaging material web 11 is regulated or detected as needed. If the transport speed of the packaging material web 11 is predetermined or known, and the at least on sensor 16 has also detected where control marks 5 are located on the packaging material web 11, it is clear when the laser units 17 must begin a line of weakness 7 and how the laser beam 8 must be guided for inscribing the line of weakness 7 so that the lines of weakness 7 are respectively present at the desired location and in the desired shape on the packaging blanks 12. For the respective control of the laser units 17, a control device 18 is provided which, upon detection of at least one control mark 5 by the at least one sensor 16, receives a corresponding signal from the sensor 16.

[0054] For inscribing the lines of weakness 7 on the packaging material web 11 four laser units 17 are provided in the illustrated and in this respect preferred weakening device 14. The laser units 17 inscribe lines of weakness 7 in rows 13 on the packaging material web 11, arranged adjacent to each other and transverse to the transport direction T of the packaging material web 11. Each of the laser units 17 is assigned to a row 13 of subsequent packaging blanks 12. In the area in which the laser unit 17 inscribes the packaging material 4 with a laser 8, the packaging material web 11 is aligned between two rollers 19 at least approximately in one plane in order to also inscribe two-dimensional shapes 10 into the packaging material 4 with the line of weakness 7, without thereby being required to take into account any possible curvature of the packaging material web 11. After the packaging material web 11 has passed all four laser units 17, all desired lines of weakness 7 are inscribed into the packaging material 4, which is subsequently fed to a scoring station, in which the score lines 6 are applied to the packaging material web 11. The packaging material 4 or the packaging material web 11 is transported past the laser units 17 by means of a transport device 39.

[0055] FIG. 4A shows a detail of the weakening device 14 from FIG. 3. Between the laser unit 17 and the packaging material web 11, an extractor hood 20 is respectively provided. Alternatively, several or all extractor hoods 20 may be combined. For the sake of clarity, the extractor hoods 20 are not shown in FIG. 3. The extractor hoods 20 are open adjacent to the packaging material web 11 and spaced apart from the packaging material web 11 by a gap 21. The extractor hoods are connected to the associated laser unit 17, wherein the laser unit 17, in particular the focussing optics 27 and/or the scanner 29, has a glass pane or a housing section 22 transparent to the laser beam 8, through which the laser beam 8 can be directed into the extractor hood 20 and towards the packaging material 4. The extractor hood 20 thus comprises, if necessary, the transparent pane or the transparent housing section 22 of the laser unit 17. In other words, the extractor hood 20 adjoins the transparent pane or the transparent housing section 22 of the laser unit 17. The extractor hood 20 is also associated with an exhaust 23, via which air is withdrawn from the extractor hood 20, which extracts the packaging material 4 removed by the laser 8.

[0056] FIG. 4B shows a similar detail as in FIG. 4A of an alternative weakening device, for which reason the same reference numerals are used. Between the laser unit 17 and the packaging material web 11, an extractor hood 20 is provided, which is spaced apart from the laser unit 17 and has a transparent pane or a transparent housing section 22 through which the laser beam 8 can enter the extractor hood 20 and reach the packaging material. A connection between the extractor hood 20 and the associated laser unit 17 is not required. The extractor hood 20 shown in FIG. 4B is also open adjacent to the packaging material web 11 and is spaced apart from the packaging material web 11 by a gap 21. The extractor hood 20 is also similarly assigned an exhaust 23, via which air is withdrawn from the extractor hood 20, which extracts the packaging material 4 removed by the laser 8.

[0057] In FIG. 5, the laser unit 17 of the weakening device 14 is shown schematically. The laser unit 17 comprises a laser 24 or a laser source for generating a laser beam 8. The laser 24 first passes through a shutter 25 in its beam path. The shutter 25 closes and opens repeatedly at very short intervals. When the shutter 25 is closed, the laser beam 8 does not pass through the shutter 25. However, when the laser beam 8 is opened, the laser beam 8 does pass through. If the shutter 25 is open for a longer period of time and closed for a shorter period of time, more energy is transferred to the packaging material 4 and vice versa. After passing through the shutter 25, the laser beam 8 enters a beam switch 26, which can occupy two positions. In the liner position, the laser beam 8 is directed to a focussing optics 27, which focuses the laser beam 8 onto the plane of the packaging material 4. In the illustrated and in this respect preferred laser unit 17, a deflection mirror 28 is provided between the beam switch 26 and the focussing optics 27. With the beam switch 27 in the liner position, the laser beam 8 of the laser unit 17 inscribes a straight line of weakness 7 in the packaging material 4. Thus, for example, packaging blanks 1 according to FIG. 1A can be obtained.

[0058] In order to obtain packaging blanks 2, 3 according to FIGS. 1B-C, the beam switch 26 must be adjusted from the liner position to the scanner position. In the scanner position, the beam switch 26 directs the laser beam 8 entering the beam switch 26 onto a scanner 29. In the illustrated and in this respect preferred laser unit 17, the laser beam 8 also passes through a fixedly mounted deflection mirror 30 and a further focussing optics 33. Both could in principle be dispensed with or could be provided elsewhere in the beam path.

[0059] The scanner 29 has, in the illustrated and in this respect preferred laser unit 17, a mirror 32 which can be pivoted about two mutually perpendicular axes. In principle, however, two separate mirrors pivoting respectively about a different axis could be provided. By adjusting the mirror 32, the laser beam 8 can be adjusted or deflected in a direction parallel to the transport direction T of the packaging material web 11 (x-direction) and alternatively or additionally in a direction perpendicular to the transport direction T and parallel to the packaging material web 11. As a result of this deflection, lines of weakness 7 can be inscribed in the packaging material 4, forming a two-dimensional shape 9, 10.

[0060] The laser beam 8 can thus move over the packaging material 4 by an adjustment of the scanner 29, as shown in FIG. 6. The scanner 29 can be adjusted specifically parallel to the transport direction T of the packaging material 4 (x-direction) or perpendicular thereto along the packaging material 4 (y-direction). The line of weakness 7 then runs on the packaging material 4 at least also in a direction transverse to the transport direction T of the packaging material web 11.

[0061] If the laser beam 8 is deflected very far in the x-direction and/or y-direction relative to a starting position, the path of the laser beam 8 between the laser unit 17 and the packaging material 4 becomes longer in the direction of the beam path of the laser beam 8 (z-direction). In contrast, the z-coordinate becomes generally shorter when the laser beam 8 is adjusted less far from a central starting position in the x-direction and/or y-direction. Regardless of the respective deflection of the laser beam 8, the focus of the laser beam 8 should still be in the plane of the packaging material 4. Therefore, a further focussing optics 33 is provided in the beam path of the laser beam 8 passing through the scanner 29, which makes this possible. This can for example have a lens 34 which is adjustable in the direction of the beam path. The adjustment of the lens 34 can then be controlled by the scanner 29 depending on the adjustment of the laser beam 8.

[0062] In FIGS. 7A-B, the beam switch 26 is shown in detail. The beam switch 26 has a drive 35, in particular pneumatic or alternatively electric, which is designed as a pneumatic double piston drive. To move the pistons, two compressed air connections 36, 37 are provided. If compressed air is supplied to a compressed air connection 36, a mirror unit 38 of the beam switch 26 is arranged in the liner position shown in FIG. 7A, so that the laser beam 8 is directed to the focussing optics 27 and a straight line of weakness 7 is inscribed into the packaging material 4. If now another piston is supplied with compressed air via the other compressed air connection 37, the mirror unit 38 of the beam switch 26 rotates into the scanner position shown in FIG. 7B, in which the beam switch 26 directs the laser beam 8 to the scanner 29 in order to to inscribe a two-dimensional shape 9, 10 into the packaging material 4 by means of the line of weakness 7. If necessary, the mirror unit 38 can be rotated back to the liner position by renewed pressurisation of the other compressed air connection 36.

LIST OF REFERENCE NUMERALS

[0063] 1 Packaging blank [0064] 2 Packaging blank [0065] 3 Packaging blank [0066] 4 Packaging material [0067] 5 Control mark [0068] 6 Score lines [0069] 7 Lines of weakness [0070] 8 Laser beam [0071] 9 Shape [0072] 10 Shape [0073] 11 Packaging material web [0074] 12 Packaging blank [0075] 13 Row [0076] 14 Weakening device [0077] 15 Packaging material roll [0078] 16 Sensor [0079] 17 Laser unit [0080] 18 Control device [0081] 19 Rollers [0082] 20 Extractor hood [0083] 21 Gap [0084] 22 Housing section [0085] 23 Exhaust [0086] 24 Laser [0087] 25 Shutter [0088] 26 Beam switch [0089] 27 Focussing optics [0090] 28 Deflection mirror [0091] 29 Scanner [0092] 30 Deflection mirror [0093] 32 Mirror [0094] 33 Focussing optics [0095] 34 Lens [0096] 35 Drive [0097] 36 Compressed air connection [0098] 37 Compressed air connection [0099] 38 Mirror unit [0100] 39 Transporting means