Method for applying a cover strip and a tear-strip to a closure flap of a mailing bag

Abstract

Main claim: A method for applying at least one cover strip (4) and at least one tear-strip (6) to a closure flap (8) of a mailing bag (10) or of a packaging product, in which at least one cover strip web (12, 12a, 12b) with glue applied to it and at least one tear-strip web (22) with glue applied to it or self-adhesive are guided onto a rotating feed cylinder (28) and on same are subdivided into the cover strip (4) and tear-strip (6) by means of an associated knife shaft (30), which strips are then applied by the feed cylinder (28) simultaneously onto the closure flap (8) of the mailing bag (10) traveling past.

Description

[0001] TERGAU & WALKENHORST Page 1 P220487DE 24. Mai 2024Claims 1. A method for applying at least one cover strip (4) and at least one tear strip (6) to a closure flap (8) of a shipping bag (10) or a packaging product, wherein at least one cover strip web (12, 12a, 12b) provided with an adhesive application and at least one tear strip web (22) provided with an adhesive application or self-adhesive are guided onto a rotating feed cylinder (28) and are divided on this by means of an associated cutter shaft (30) into cover strips (4) and tear strips (6), which are then applied by the feed cylinder (28) simultaneously to the closure flap (8) of the passing shipping bag (10). 2. Method according to claim 1, wherein the cover strip web (12, 12a, 12b) and the tear strip web (22) are guided over a common, driven feed roller (24) before reaching the feed cylinder (28). 3.Method according to claim 2, wherein the cover strip web (12, 12a, 12b) is guided between the feed roller (24) and the feed cylinder (28) past a glue application head (26), which applies glue, in particular hot melt glue, to one side of the cover strip web (12, 12a, 12b). 4. Method according to claim 3, wherein the tear strip web (22) is self-adhesive and is guided onto the feed cylinder (28) bypassing the glue application head (26). 5. Method according to any one of the preceding claims, wherein two cover strips (4) and a tear strip (6) placed between them are applied to the closure flap (8) in a parallel arrangement. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: May 24, 2024 TERGAU & WALKENHORST Page 26. The method of claim 5, wherein a single cover strip web (12) is split into two parallel cover strip webs (12a, 12b) by a longitudinal cutting unit (16). 7.Method according to one of the preceding claims, wherein the respective cover strip (12, 12a, 12b) and the tear strip (22) are held on the feed cylinder (28) by vacuum suction. System (2) for applying at least one cover strip (4) and at least one tear strip (6) to a closure flap (8) of a shipping bag (10) or a packaging product, the system (2) comprising a feed cylinder (28) and an associated cutter shaft (30), which are arranged such that at least one cover strip web (12, 12a, 12b) provided with an adhesive coating and at least one tear strip web (22) provided with an adhesive coating or self-adhesive can be guided onto the feed cylinder (28) and can be subdivided on it by means of the cutter shaft (30) into cover strips (4) and tear strips (6), which can then be applied simultaneously by the feed cylinder (28) to the closure flap (8).10. System (2) according to claim 8, wherein a common, driven feed roller (24) for the cover strip web (12, 12a, 12b) and the tear strip web (22) is arranged upstream of the feed cylinder (28). 11. System (2) according to claim 9, wherein the diameter of the feed roller (24) in a circumferential zone (54) for the tear strip web (22) differs from the diameter in a circumferential zone (52) for the cover strip web (12a, 12b). 12. System (2) according to claim 10, wherein the different circumferential zones (52, 54) of the feed roller (24) are formed by interchangeable discs. 13. Plant (2) according to one of claims 8 to 11, wherein a glue application head (26) for applying glue, in particular hot melt glue, to one side of the cover strip web (12, 12a, 12b) is arranged between the feed roller (24) and the feed cylinder (28). (Z:\DOCUMENT\AMT\2142196.docx) Last saved: May 24, 2024 TERGAU & WALKENHORST Page 314. System (2) according to any one of claims 8 to 12, wherein the system (2) comprises a longitudinal cutting unit (16) which splits a single cover strip web (12) into two parallel cover strip webs (12a, 12b). 15. System (2) according to any one of claims 8 to 13, wherein the feed cylinder (28) has a plurality of radial bores (38) for vacuum suction of the cover strip web (12, 12a, 12b) and the tear strip web (22). 16. System (2) according to any one of claims 8 to 14, wherein the feed cylinder (28) has an at least partially lowered circumferential guide for the tear strip web (22) in which the tear strip web (22) preferably lies with inwardly curved edges. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: 24.May 2024 TERGAU & WALKENHORST Page 4 Description Method for Applying a Cover Strip and a Tear Strip to a Closure Flap of a Shipping Bag The invention relates to a method for applying at least one cover strip and at least one tear strip to a closure flap of a shipping bag or packaging product. It further relates to a device (apparatus) suitable for carrying out the method. Shipping bags for letters and goods typically have a closure flap provided with at least one cover strip and a tear strip. "Cover strip" refers in particular to a protective strip that covers an underlying layer or layer of adhesive. When the protective strip is removed, it exposes the adhesive, allowing the closure flap to be folded over and thus sealed to a corresponding surface of the shipping bag.With the aid of the tear strip, which also adheres to the closure flap by means of an adhesive or glue layer, the protective flap of the shipping bag can be reopened as needed. A second cover strip can be provided for resealing, for example, in the case of returns. The object of the invention is to provide a simple method and a simple system with which the application of cover strips and tear strips to closure flaps of shipping bags or the like can be carried out efficiently and reliably in an automated manner, in particular at a high cycle rate. The object is achieved according to the invention by a method with the features of claim 1 and a system with the features of claim 8. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: 24.May 2024 TERGAU & WALKENHORST Page 5 Accordingly, a method is provided for applying at least one cover strip and at least one tear strip to a closure flap of a shipping bag or packaging product, in which at least one cover strip web coated with adhesive and at least one tear strip web coated with adhesive or self-adhesive are guided onto a rotating feed cylinder and divided on this cylinder into cover strips and tear strips by means of an associated cutter shaft, which are then simultaneously applied by the feed cylinder to the closure flap of a passing shipping bag. The tasks, features, embodiments, and advantages with regard to the method are transferred analogously to the system and vice versa. Advantageous embodiments are the subject of the dependent claims and the following detailed description.Advantageously, the cover strip web and the tear strip web are guided over a common, driven feed roller before reaching the feed cylinder. This keeps the number of components to a minimum, and the web speeds can be easily and reliably adjusted or synchronized. Furthermore, it is preferred that the cover strip web is guided past a glue application head between the feed roller and the feed cylinder, which applies glue, particularly hot melt glue, to one side of the cover strip web. The tear strip web, on the other hand, is preferably self-adhesive and therefore does not require any further glue application. It is therefore preferably guided onto the feed cylinder bypassing the glue application head. In an advantageous embodiment, with regard to the most common configuration of the end product, two cover strips and a tear strip between them are applied to the closure flap in a parallel arrangement.It is particularly advantageous if a single cover strip is split into two parallel cover strips by a longitudinal cutting unit. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: May 24, 2024 TERGAU & WALKENHORST Page 6. Only a single supply roll for the cover strip is required.With regard to the device, the present invention provides a system for applying at least one cover strip and at least one tear strip to a closure flap of a shipping bag or packaging product. The system comprises a feed cylinder and an associated cutter shaft, which are arranged such that at least one cover strip web coated with adhesive and at least one adhesive-coated or self-adhesive tear strip web can be guided onto the feed cylinder and subdivided on the feed cylinder into cover strips and tear strips by means of the cutter shaft. These strips can then be applied simultaneously to the closure flap by the feed cylinder. In an advantageous embodiment, a common, driven feed roller for the cover strip web and the tear strip web is arranged upstream of the feed cylinder.By having a different diameter in a circumferential zone of the feed roller for the tear strip web compared to a different diameter in a circumferential zone for the cover strip web, the length of the tear strip can differ from that of the cover strip. The term "circumferential zone" here and in the following preferably refers to an annular section of the outer surface of the respective roller. It is particularly advantageous if the different circumferential zones of the feed roller are formed by interchangeable discs that are firmly but detachably connected to one another, so that a desired change in diameter can be achieved by replacing one or more discs. Advantageously, a glue application head for applying glue, especially hot melt glue, to one side of the cover strip web is arranged between the feed roller and the feed cylinder. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: 24.May 2024 TERGAU & WALKENHORST Page 7 As already mentioned in connection with the process, the system preferably has a longitudinal cutting unit that splits a single cover strip web into two parallel cover strip webs (partial webs). Furthermore, it is advantageous if the feed cylinder has a plurality of radial bores for vacuum suction of the cover strip web and the tear strip web. In other words, the respective cover strip web and the tear strip web are held on the feed cylinder by vacuum suction. Finally, for reliable web guidance, it is advantageous if the feed cylinder has at least a partially lowered circumferential guide for the tear strip web, in which the tear strip or the corresponding web preferably lies with inwardly curved edges. An embodiment of the invention is explained in more detail with reference to the accompanying drawings. It shows: FIG.1 A perspective view of a system for the simultaneous application of at least one cover strip and one tear strip to a closure flap of a shipping bag, FIG. 2 A perspective view of a feed cylinder of the system according to FIG. 1, FIG. 3 A top view of the outer surface of the feed cylinder according to FIG. 1. FIG. 2,FIG. 4 a detail from FIG. 3, FIG. 5 a perspective view of a preferred roll of the system according to FIG. 1, (Z:\DOCUMENT\AMT\2142196.docx) last saved: May 24, 2024 TERGAU & WALKENHORST Page 8, FIG. 6 a top view of the preferred roll according to FIG. 5, and FIG. 7 a shipping bag with a closure flap on which two cover strips and a tear strip are arranged. Identical parts are provided with the same reference numerals in all figures. The system 2 shown schematically in FIG. 1, in a preferred embodiment, serves for the simultaneous application of two hot melt adhesive cover strips 4 and a self-adhesive tear strip 6 to a closure flap 8 of a shipping bag 10 or a similar packaging product. For this purpose, Annex 2 has a (not shown) supply roll from which an (endless) cover strip roll 12 is unwound during operation.The cover strip web 12 is guided past a longitudinal cutting unit 16 via a number of deflection rollers 14. The longitudinal cutting unit 16 has a rotating circular blade 18 and a counter roller 20 with a corresponding groove. The longitudinal cutting unit 16 cuts the cover strip web 12 longitudinally into two cover strip webs 12a, 12b, preferably of the same width, which are then transported further parallel to each other at a predetermined distance. For this purpose, the two cover strip webs 12a, 12b are first moved apart by a suitable guide. The distance is dimensioned such that a tear strip web 22 (optionally with a gap or with a one-sided or two-sided gap) can be placed between the cover strip webs 12a, 12b further downstream in the transport direction.The two separated cover strip webs 12a, 12b are guided parallel to each other over a number of deflection rollers 14 and a driven feed roller 24, which advances the webs or assists this in combination with other drive means. From there, the cover strip webs 12a, 12b are guided over a number of deflection rollers 14 past a glue application head 26, which applies a layer of glue, in particular hot melt glue, to one side of the webs. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: May 24, 2024 TERGAU & WALKENHORST Page 9. Subsequently, the two glued cover strip webs 12a, 12b, with the glue layer facing outwards, are placed parallel to each other and at the set distance from each other onto the circumference (i.e., the outer surface) of a rotating feed cylinder 28 with vacuum suction.By means of a rotating cutter shaft 30 interacting with the feed cylinder 28, the two cover strip webs 12a, 12b are divided into cover strips 4 of defined length by transverse cuts and, after passing through a defined angle of rotation at a transfer point, here at the lowest point of the feed cylinder 28, are unwound tangentially onto a shipping pouch 10 (not shown in FIG. 1) running horizontally past it and applied. The transport of the shipping pouches 10 can be carried out on a roller unit 32 as shown. The direction of rotation of the feed cylinder 28 and the feed direction of the shipping pouches 10 are indicated by arrows in FIG. 1. Furthermore, the system 2 has a supply roll (not shown) from which a ("continuous") tear strip web 22 is unwound during operation. This is preferably a self-adhesive web with an adhesive film on one side.During subsequent transport over various rollers, the adhesive film is preferably always held on the outside, on the side facing away from the roller. However, this is not strictly necessary when using non-stick coated rollers. The transport of the tear-off strip web 22 preferably takes place in a plane that is parallel to or identical with the transport plane of the cover strip web 12. The tear-off strip web 22 is guided over a deflection roller unit 34 with a plurality of deflection rollers arranged in a zigzag configuration. The deflection roller unit 34, also referred to as a "dancer," serves to adjust the web tension. From there, the tear-off strip web 22 is guided over the feed roller 24, which also advances the cover strip web 22, such that the tear-off strip web 22 is guided in the gap between the two cover strip webs 12a, 12b.After passing the feed roller 24, the tear strip web 22 is placed between the cover strip webs 12a, (Z:\DOCUMENT\AMT\2142196.docx) last saved: May 24, 2024TERGAU & WALKENHORST Page 10 12b on the circumference (i.e. the outer surface) of the rotating feed cylinder 28 with vacuum suction, via a number of deflection rollers 36, bypassing the glue application head 26. In this example, the bypass path lies above the glue application head 26. By means of the rotating knife shaft 30, which interacts with the feed cylinder 28, the tear strip web 22 is divided into tear strips 6 of defined length by transverse cuts and, after passing through a defined angle of rotation at the transfer point, here at the lower low point of the feed cylinder 28, is unrolled tangentially onto a shipping bag 10 running in a horizontal direction and applied.The application of the tear strip 6 proceeds analogously and simultaneously with the application of the cover strips 4 using the feed cylinder 28. The blades of the cutter shaft 30 cut the cover strip webs 12a, 12b and the tear strip web 22 simultaneously. As can be seen in FIGS. 2 and 3, the feed cylinder 28 has three circumferential zones on its surface, each provided with radial bores 38 for vacuum suction: two ring-shaped outer circumferential zones 40 for the cover strips (webs) and, located between them, a ring-shaped middle or inner circumferential zone 42 for the tear strip (web). Transverse grooves 44 form counter-pressure points for the cutting blades of the cutter shaft 30. Additionally or alternatively, cutter bars can be inserted into the transverse grooves 44. The bearing surfaces for the cover strips (-sheets) are preferably flat in cross-section, as can be seen in the detailed illustration according to FIG. 4.This means that the radius of the feed cylinder 28 is essentially the same and constant in cross-section. The inner circumferential zone 42 for the tear strip (or strip), however, has a non-constant height profile in cross-section, preferably symmetrical about a center line 46, as can also be seen in FIG. 4. In the region of the center line 46, the radius of the feed cylinder 28 is preferably essentially the same as the radius in the two outer circumferential zones 40; however, towards the outer edge of the inner circumferential zone 42, the radius becomes somewhat smaller. In other words, the inner circumferential zone 42 for the tear strip 6 has a relative elevation in the center, where radial bores 38 for vacuum suction are also centered, and a relative depression towards the outside. The transition (Z:\DOCUMENT\AMT\2142196.docx) last saved: May 24, 2024.

Claims

TERGAU & WALKENHORST, page 11, shows that the two outer circumferential zones 40 for the cover strips 4 have a slight height difference with lateral flanks 48. This geometry causes the applied and drawn-in tear strip 6 to curve slightly inwards at both edges and, in a sense, to lie in a lowered bed with lateral guidance – without being able to slip laterally towards the cover strips 4. The local depressions can be introduced into the feed cylinder 28 during manufacturing, for example, by a rotary tool. The feed roller 24, shown in FIGS. 5 and 6 together with a drive shaft 50, causes, as already mentioned, the simultaneous feeding of the cover strip webs 12a, 12b and the tear strip web 22. Similar to the feed cylinder 28, the feed roller 24 has three adjacent circumferential zones, but here without suction bores.Each of the circumferential zones is flat in cross-section, with the radius of the pre-roller 24 being the same in the two outer circumferential zones 52 for the cover strip webs 12a, 12b. In the middle or inner circumferential zone 54 for the tear strip web 22, however, the radius of the pre-roller 24 can differ. This allows the length ratio of cover strip 4 to tear strip 6 to be influenced. Advantageously, the pre-roller 24 comprises three stacked discs, the discs being interchangeable (in particular, the middle disc is interchangeable) to adjust the ratio of the radii (and thus the strip lengths) by changing the discs.It should be noted that the strips are placed with "slip" onto the rotating feed cylinder 28, so that they ultimately lie flush on one side of the closure flap 8 due to the simultaneous (parallel) cut, but a length variation can occur on the other side as described (see FIG. 7). Possible modifications of the described concept include the case where only a single cover strip is applied. The longitudinal cutting unit can then be omitted. Furthermore, the cover strip can be self-adhesive; then no glue application head is required for the cover strip web. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: May 24, 2024 TERGAU & WALKENHORST Page 12 It is also possible that the tear strip is not self-adhesive, but is glued in the system by means of a glue application head. (Z:\DOCUMENT\AMT\2142196.docx) Last saved: 24.May 2024 TERGAU & WALKENHORST Page 13 Reference list. 2 Anlage 4 Cover strip 6 Tear strip 8 Closure flap 10 Shipping bag 12, 12a, 12b Cover strip web 14 Deflection roller (for the cover strip web) 16 Longitudinal cutting unit 18 Circular knife 20 Counter roller 22 Tear strip web 24 Pre-roller 26 Glue application head 28 Feed cylinder 30 Knife shaft 32 Roller unit 34 Deflection roller unit (dancer) 36 Deflection roller (for the tear strip web) 38 Radial bore 40 Outer circumferential zone (of the feed cylinder) 42 Inner circumferential zone (of the feed cylinder) 44 Transverse groove 46 Center line 48 Flanke 50 Drive shaft 52 Outer circumferential zone (of the pilot roller) 54 Inner circumferential zone (of the pilot roller) (Z:\DOCUMENT\AMT\2142196.docx) Last saved: May 24, 2024

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