Apparatus for forming bags having a folded bottom

Abstract

The invention relates to a device for producing bags with a folded bottom section from a flat, open-ended section of tubing, comprising at least two folding stations, each comprising a folding drum with at least one axially extended clamping device arranged on / in or below the drum surface, having two clamping jaws, and a knife shaft radially spaced from the folding drum, with at least one axially extended folding knife, wherein, during rotation of the folding drum and knife shaft, a folding knife can be immersed at least partially in a gap between the clamping jaws, a feeding device with which a section of tubing can be fed in a conveying plane to the folding drum of a first folding station substantially tangentially to the drum surface of the folding drum, and a transfer device between folding stations adjacent in the conveying direction.with which the hose section can be transferred tangentially to the drum surfaces between the folding drums of the adjacent folding stations, a depositing station after the last folding station in the conveying direction, into which the hose section can be deposited, wherein with each folding station a leading area of ​​a hose section conveyable by the folding station can be folded around a fold line onto the hose section, so that a hose section conveyed by all folding stations has a closed bottom after the last folding station, with a number of folds corresponding to the number of folding stations.

Description

[0001] The invention relates to a device for the production of bags, in particular paper bags, with a folded bottom area made from a flat, open-ended section of tubing, in particular a paper tubing section.

[0002] The term "flat lying" here means that the hose section lies flat, so that the opposing surfaces of the hose section contact each other, in particular over the entire surface, preferably forming a respective lateral fold that runs between the open ends.

[0003] The production of bags from a section of tubing is generally known. According to the prior art, a plastic material or a paper composite material with a high plastic content is typically used as the tubing section, and one of the open ends is then thermally welded to form a bag closed on one side. It is also known to fold over an open end section of the tubing before welding to reinforce the end.

[0004] For reasons of sustainability and environmental protection, the industry is increasingly striving to switch to pure paper in the production of bags, e.g., those for food, or at least to paper composite materials with a very low plastic content, preferably less than 10%, and more preferably less than 5%. However, a tube made from such a material can no longer be thermally welded.

[0005] Against this background, an object of the invention is to provide a device that makes it possible to form a hose section open at both ends into a bag closed at one end without thermal welding, in particular so that the bag is also liquid-tight at the formed bottom area. Preferably, the invention should also make it possible to produce paper hoses made of pure paper or with a maximum plastic content of less than 10%, preferably less than 5%.

[0006] This problem is solved by a device of the type mentioned above, which comprises at least two folding stations, each folding station comprising a folding drum with at least one axially extended clamping device arranged on / in or below the drum surface, having two clamping jaws, preferably at least one of which is movable, and comprising a cutter shaft radially spaced from the folding drum, with at least one axially extended folding knife, wherein, during the rotation of the folding drum and cutter shaft, a respective folding knife can be immersed at least partially in a gap area between the clamping jaws of a clamping device, and which further comprises a feeding device with which a hose section can be fed in a conveying plane to the folding drum of a first folding station substantially tangentially to the drum surface of the folding drum, and which comprises a transfer device between folding stations adjacent in the conveying direction.with which the hose section can be transferred tangentially to the drum surfaces between the folding drums of the adjacent folding stations, and which comprises a depositing station after the last folding station in the conveying direction, into which the hose section can be deposited, in particular in a plane oriented perpendicular to the conveying plane, wherein with each folding station a portion of a hose section conveyable by the folding stations, which is leading in the conveying direction, can be folded around a fold line onto the hose section, in particular by the action of a folding knife and clamping device and preferably further devices, so that a hose section conveyed by all folding stations has a closed bottom after the last folding station, with a number of folds corresponding to the number of folding stations, wherein the number of folds is at least two.

[0007] With such a device and a number of at least two folds, a dense bottom area can be achieved even when using hose sections made of pure paper or with a very low plastic content, because the bottom has sufficient inherent stability due to the at least two folds.

[0008] The folding process involves folding the hose section, conveyed to a first folding station, around a fold line at its leading end (i.e., the section at the front in the transport direction) at a distance from the leading end, which is still open at the first folding station. The fold is created by the folding knife pressing the hose section into the clamping device at the location of the fold line between the folding drum and the cutter shaft. This causes the leading end of the hose section to rise out of the conveying plane and then be folded over onto the section of the hose that lies behind the fold line in the conveying direction.

[0009] Such a folding after raising can preferably be carried out by means of a folding device by pressing the leading raised hose section onto the hose section following the fold line.

[0010] Such a laying device preferably comprises at least one roller. For example, the laying device can also form an arrangement of several rollers around which a belt is laid.

[0011] A transfer device is preferably arranged trailing each folding station or each cutter shaft in the conveying direction of the hose section. Particularly in the case of a folding drum that is the last in the conveying direction, it can be in contact with the folding drum or have a distance from the folding drum corresponding to the paper thickness after the transfer. Preferably, particularly between adjacent folding drums, it can be in contact with the transfer device or have a distance from the transfer device corresponding to the paper thickness after the transfer.

[0012] Preferably, a gap is formed between the folding device and the folding drum or transfer device, through which the hose section with the raised leading end is passed, causing the folding action.

[0013] The transport to at least one further folding station after the initial folding allows for at least one more folding, resulting in a dense bottom area.

[0014] Preferably, it is further provided that, at least at the last folding station, an application device is assigned to each folding knife of the cutter shaft, lagging behind the cutter shaft in the direction of rotation, with which adhesive can be applied to a region of the hose section lagging behind the fold line, which can be covered by the folded, leading region. This ensures that the folded region, preferably at least in the last fold, and more preferably in every fold, is additionally held in contact with the surface of the hose section by adhesive bonding. Such bonding preferably occurs in every fold, so that the resulting bottom section is bonded multiple times, in particular at least twice.

[0015] Preferably, the aforementioned folding device is used to press the leading hose section into the previously applied adhesive. For this purpose, the application device is arranged in the conveying direction upstream of the folding device. Preferably, each folding knife has its own application device, which rotates with it around the knife shaft. Preferably, a knife shaft has exactly two, or at least two, folding knives and application devices arranged around the knife shaft.

[0016] Preferably, all folding stations in the device are driven synchronously. This can be achieved, for example, by mechanically coupling the folding drums and / or knife shafts to each other, in particular by driving them with the same drive, or by electronically synchronizing them if they are driven by separate drives.

[0017] It is further preferred that the phase shift of the rotation angle positions, and in particular the folding times, between the folding stations is adjustable. This makes it possible to individually adjust the distance of the fold line from the leading end of the hose section at each folding station.

[0018] For example, the device may be designed to carry out the folding with an increasing distance of the fold line from the leading end of the hose section from folding station to folding station.

[0019] This ensures that the fold line always occurs within a single layer thickness of the hose section. The next fold is always made within a previously unfolded area of ​​the hose section. This results in the bottom section having a thickness of n+1 layers of hose section after n folds.

[0020] It can also be provided that the device is configured to perform the folding with a decreasing distance of the fold line from the leading end of the tube section from folding station to folding station. This allows for a greater number of layers in the bottom area of ​​the bag compared to the aforementioned design. A subsequent fold is thus made in an area that already has an increased number of layers due to the previous fold. This allows a comparatively thick, heavy bottom area to be created with fewer folds.

[0021] To facilitate transfer between adjacent folding stations, the invention preferably provides that, after insertion of the hose section between the clamping jaws of the clamping device by means of the folding knife, the hose section is held clamped by the clamping device over a rotation angle range of less than 20 degrees, preferably less than 10 degrees. This ensures reliable onward transport without lowering the hose section too far from the conveying plane due to the rotation of the folding drum and allows for safe transfer to the transfer device, which can preferably be positioned close to and surrounding the folding drum up to just before the clamping angle range.

[0022] The last folding station is preferably configured, after the hose section has been inserted between the clamping jaws of the clamping device by means of the folding knife, to hold the hose section clamped by the clamping device over a rotation angle range greater than 45 degrees, preferably greater than 65 degrees. This lowers the clamped hose section through the folding drum from the conveying plane towards a depositing station, where a stack of the finished bags is formed extending in the conveying direction.

[0023] The device described above is preferably configured as a hose section to process a hose made of pure paper or a paper composite material with less than 10%, preferably less than 5%, plastic content, in particular polymer content.

[0024] An embodiment of the invention is described with reference to the Figure 1 explained.

[0025] The Figure 1 Figure 1 shows a device according to the invention with, in this case, two folding stations F1 and F2. Each folding station comprises a folding drum 1a or 1b and an associated cutter shaft 2a or 2b. In this embodiment, two folding knives 3 are attached to each cutter shaft, and an application device 5 for applying adhesive is assigned to each folding knife 3.

[0026] Distributed circumferentially over the folding drum 1a or 1b, at least one clamping device 4, here four clamping devices 4, extend in the axial direction of the drum axis on, in or under the drum surface.

[0027] The detail section at the bottom right in the Figure 1 This illustrates that during rotation, each folding knife 3 plunges into a clamping device 4, more precisely between two clamping jaws of the clamping device 4.

[0028] It is preferably provided that at least one of the clamping jaws is movable towards another. For example, one clamping jaw can be fixed, so that the other clamping jaw is moved towards the fixed one to effect clamping, or both clamping jaws can be movable towards each other. An embodiment is also possible in which the clamping jaws of the clamping device have a fixed distance, but preferably an adjustable distance, from each other.

[0029] In the device shown here, a hose section 9 is fed from the right via the feed device 6 to the first folding station F1. The feed takes place in a conveying plane that corresponds at least substantially to the upper tangential plane at both folding drums of folding stations F1 and F2.

[0030] At a distance from the open end of the hose section, the leading end area of ​​the hose section 9 is pressed between the clamping jaws of the clamping device 4 at a fold line using the folding knife 3, causing the end area of ​​the hose section 9, which lies in front of the fold line in the conveying direction, to fold up, preferably temporarily clamped between the clamping jaws, and then be folded over.

[0031] Preferably, the hose section 9 is guided along with the rotating folding drum 1a by clamping and, preferably after the clamp is released, transferred to the transfer device 7, which conveys the hose section 9 to the next folding station F2. The application device 5, which rotates behind the folding knife 3, applies adhesive to the hose section 9 in the conveying direction along the fold line, particularly adjacent to the fold line in an area of ​​the surface of the hose section 9 onto which the raised end section of the hose section 9 is folded.

[0032] The folding after the folding up / raising takes place in each folding station F1, F2 preferably by a folding device 10, which follows a respective cutter shaft 2a, 2b in the conveying direction of the hose section 9.

[0033] In this embodiment, the folding device 10, which cooperates with or is associated with the first folding station F1, comprises several rollers around which a belt runs. This folding device 10, together with the surface of the transfer device 7, forms a gap through which the folded-up end section of the hose segment 9 is guided and thereby folded over.

[0034] The bottom of the hose section 9 is folded once, whereby an adhesive bead was applied between the overlapping surfaces of the hose section 9 using the application device 5 before folding.

[0035] In the second folding station F2, the process is repeated, resulting in a bag with a double-folded bottom. At the second folding station F2, the folding / raising of the end section of the tube segment 9 in front of the folding line occurs in the same manner as previously described. Here, the folding device 10 is designed, for example, as a single roller that forms a gap with the surface of the folding drum 1b, through which the folding takes place.

[0036] The bag is preferably guided by clamping in the clamping device 4 below the conveying level to the storage device 8, where a stack of bags is formed from the folded hose sections 9.

[0037] The invention may not only include the two folding stations F1 and F2 shown here. More than two consecutive folding stations may also be provided, preferably wherein the lifting and folding between two adjacent folding stations is carried out as described here for folding station F1, and preferably the lifting and folding in the last folding station is carried out as described for folding station F2.

Claims

1. Device for producing bags, in particular paper bags, with a folded bottom section made from a flat, open-ended tube section (9), in particular a paper tube section, comprising a. at least two folding stations (F1, F2), wherein each folding station (F1, F2) comprises i. a folding drum (1a, 1b) with at least one axially extended clamping device (4) arranged on / in or below the drum surface, having two clamping jaws, preferably at least one of which is movable, and ii. a cutter shaft (2a, 2b) radially spaced from the folding drum (1a, 1b), with at least one axially extended folding knife (3), iii. wherein, during the rotation of the folding drum (1a, 1b) and the cutter shaft (2a, 2b), each folding knife (3) is at least partially immersible in a gap between the clamping jaws of a clamping device (4), b.a feeding device (6) with which a hose section (9) can be fed in a conveying plane to the folding drum (1a) of a first folding station (F1) substantially tangentially to the drum surface of the folding drum (1a), c. a transfer device (7) between folding stations (F1, F2) adjacent in the conveying direction, with which the hose section (9) can be transferred tangentially to the drum surfaces between the folding drums (1a, 1b) of the adjacent folding stations (F1, F2), d.A depositing station (8) after the last folding station (F2) in the conveying direction, into which the hose section (9) can be deposited, in particular in a plane oriented perpendicular to the conveying plane, wherein with each folding station (F1, F2) a portion of a hose section (9) conveyable by the folding station (F1, F2) that is leading in the conveying direction can be folded around a fold line onto the hose section (9), in particular by the action of folding knife (3) and clamping device (4) and preferably further devices (10), so that a hose section (9) conveyed by all folding stations (F1, F2) has a closed bottom after the last folding station (F2), with a number of folds corresponding to the number of folding stations (F1, F2), wherein the number of folds is at least two.

2. Device according to claim 1, characterized by the fact thatEach folding knife (3) of the knife shaft (2a, 2b), at least in the last folding station (F1), preferably in each folding station (F1, F2) lagging in the direction of rotation of the knife shaft (2a, 2b), is assigned an application device (5) with which adhesive can be applied to a region of the hose section (9) lagging behind the fold line, which can be covered by the folded leading region, in particular wherein the folded leading region can be folded over to the lagging region and pressed into the applied adhesive by means of a folding device (10), preferably comprising at least one roller.

3. Device according to one of the preceding claims, characterized by the fact that The folding stations (F1, F2) are all driven synchronously.

4. Device according to one of the preceding claims, characterized by the fact that The phase shift of the rotation angle positions, in particular the folding times, between the folding stations (F1, F2) is adjustable.

5. Device according to one of the preceding claims, characterized by the fact that it is set up to carry out the folding with an increasing distance of the fold line from the leading end of the hose section (9) material hose from folding station (F1) to folding station (F2).

6. Device according to one of the preceding claims, characterized by the fact that it is set up to carry out the folding with a decreasing distance of the fold line from the leading end of the hose section (9) from folding station (F1) to folding station (F2).

7. Device according to one of the preceding claims, characterized by the fact that A folding station (F1), followed by another folding station (F2), is set up to hold the hose section (9) clamped by the clamping device (4) after the hose section (9) has been inserted between the clamping jaws of the clamping device (4) by means of the folding knife (3) over a rotation angle range of less than 20 degrees, preferably less than 10 degrees.

8. Device according to one of the preceding claims, characterized by the fact that The last folding station (F2) is set up, after the hose section (9) has been inserted between the clamping jaws of the clamping device (4) by means of the folding knife (3), to hold the hose section (9) clamped by the clamping device (4) over a rotation angle range greater than 45 degrees, preferably greater than 65 degrees.

9. Device according to one of the preceding claims, characterized by the fact that It is designed as a hose section (9) to process a hose made of pure paper or a paper composite material with less than 10%, preferably less than 5%, plastic content, in particular polymer content.

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