Improved longitudinal cutting and sealing device, longitudinal cutting and sealing system and film packaging machine

Abstract

Longitudinal cut-seal device (31) for a longitudinal cut-seal system (24) of a film packaging machine (10), wherein the longitudinal cut-seal device (31) comprises a first pair of endless belts (42, 44), wherein the first pair of endless belts (42, 44) is configured to draw an upper (14) and a lower (16) film web between them and guide them in a film plane (18), and wherein the longitudinal cut-seal device (31) further comprises a sealing blade (56) for longitudinally cutting and sealing the upper (14) and the lower (16) film web, wherein the longitudinal cut-seal device (31) comprises a second pair of circulating endless belts (72, 79), wherein the sealing blade (56) is arranged between the first pair of endless belts (42, 44) and the second pair of endless belts (72, 79), wherein the first pair of circulating endless belts (42, 44) extends over at least two first rotational elements (46, 48, 49;51, 53, 54), wherein the second pair of rotating endless belts (72, 79) rotates over at least two second rotating elements (47, 46; 51, 52), wherein the first rotating elements (46, 48, 49; 51, 53, 54) and the second rotating elements (47, 46; 51, 52) have parallel axes of rotation (86, 88), wherein the first pair of endless belts (42, 44) rotates in a first plane of rotation (78), wherein the welding knife (56) extends longitudinally in a plane of welding knife (56), wherein the first plane of rotation (78) and the plane of welding knife are each perpendicular to the film plane (18), characterized in that the first plane of rotation (78) and the plane of welding knife (56) intersect each other at an angle (76), wherein the belt guide (84) each endless belt (72, 79) of the second pair of endless belts (72, 79) obliquely to a respective axis of rotation of the at least two second rotational elements (47, 46;51, 52) extends, wherein a width (92) of the second pair of endless belts (72, 79) is smaller than a width (94) of the first pair of endless belts (42, 44), and wherein the longitudinal separation welding device (31) has a drive device (90), wherein the drive device (90) drives the first pair of endless belts (42, 44) and the second pair of endless belts (72, 79) together.

Description

[0001] The present invention relates to a longitudinal cutting and welding device for a longitudinal cutting and welding system of a film packaging machine, wherein the longitudinal cutting and welding device has a first pair of endless belts, wherein the first pair of endless belts is designed to pull an upper and a lower film web between them and to guide them in a film plane, and wherein the longitudinal cutting and welding device further has a welding knife for longitudinally cutting and welding the upper and the lower film web, wherein the first pair of endless belts rotates in a first circumferential plane, wherein the welding knife extends longitudinally in a welding knife plane, wherein the first circumferential plane and the welding knife plane each run perpendicular to the film plane.

[0002] Furthermore, the present invention relates to a longitudinal cutting and welding system with at least one such longitudinal cutting and welding device and a film packaging machine.

[0003] Such a longitudinal cutting and sealing device, such a longitudinal cutting and sealing system and such a film packaging machine are known, for example, from the document EP 2 332 843 B1.

[0004] Film wrapping machines have long been known in the field of industrial technology. They are used, in particular, to produce packaging for all kinds of goods. For example, data storage media such as DVDs or CDs are regularly sold wrapped in film. Newspapers with inserts, books, spare parts, and all kinds of items sold in supermarkets are also commonly provided with film wrapping.

[0005] When it comes to film packaging machines, a basic distinction is made between two types of systems: form-shoulder machines and series packaging machines.

[0006] With form-shoulder machines, a forming shoulder is first used to form a film half-tube, which is then placed around the product to be packaged. A cross-cutting welding device is then used to seal and cut the front side of the film half-tube, usually in relation to the film transport direction. The product is then moved forward, and the remaining open long side of the film half-tube is sealed using a long-cutting welding device, and the excess film is cut off. The product has now moved through the cross-cutting welding device, so that a rear transverse side is now sealed and cut off, which simultaneously represents the cross-cutting process for the front side of the subsequent product. With form-shoulder machines, three sides are thus sealed.

[0007] In series packaging machines, one film web is placed around the packaged goods from above and one from below. The two film webs thus wrap the packaged goods. Often, the upper film and the lower film are then first welded together and separated by a cross-cutting welding device on a side of the packaged goods that is at the front in relation to the transport direction of the films, and the packaged goods are then passed through a longitudinal welding system. Such a longitudinal welding system has a longitudinal welding device on each side so that the upper and lower film are welded lengthwise on both sides and any excess film is cut off. The packaged goods have then moved through the cross-cutting welding device, so that the upper and lower film can now be welded and separated on a rear side of the packaged goods using the cross-cutting welding device.In principle, however, it can also be provided alternatively that the films are first welded longitudinally and only then is the upper and lower films subsequently welded transversely.

[0008] The improvements presented in the context of this invention are preferably intended for use in series packing machines, but can in principle also be used in form-shoulder machines.

[0009] The document EP 2 380 727 B1 shows a cutting-welding knife for cutting and welding film regions lying on top of one another, with two connecting sections for resistance heating of the cutting-welding knife, and with a cutting bracket which connects the connecting sections to one another and has a straight section and two curved sections, wherein a heating element connected to the straight section is further provided, and wherein the straight section and the two curved sections are designed such that their respective conductor cross-sections are of the same size.

[0010] DE 100 21 470 A1 discloses a tubular bag packaging machine with a longitudinal sealing station designed to prevent the film from forming waves or wrinkles in the area of ​​the sealing blade whose curvature axis is parallel to the transport direction. For this purpose, transverse stretching devices are used that exert a limited transverse force on the film web. The transverse stretching devices are therefore effective in the immediate vicinity of the sealing tool.

[0011] Such a cutting-welding knife can be used in particular, for example, in a longitudinal cutting-welding device according to the document EP 2 332 843 B1 mentioned at the beginning.

[0012] We continually strive to improve the quality of the cut-off weld seam. In particular, we strive to make this improvement in the quality of the cut-off weld seam available for the widest possible range of film thicknesses and film materials. In particular, we aim to be able to process as many film materials as possible, such as polypropylene, polyethylene, or polyolefins, in various thicknesses while maintaining consistent quality.

[0013] An object of the present invention is therefore to provide an improved longitudinal cutting and welding device, a corresponding longitudinal cutting and welding system and a corresponding film packaging machine.

[0014] According to a first aspect of the invention, a longitudinal cutting and welding device for a longitudinal cutting and welding system of a film packaging machine is therefore provided, wherein the longitudinal cutting and welding device comprises a first pair of endless belts, wherein the first pair of endless belts is designed to pull an upper and a lower film web between them and to guide them in a film plane, and wherein the longitudinal cutting and welding device further comprises a welding blade for longitudinally cutting and welding the upper and lower film webs, the longitudinal cutting and welding device comprises a second pair of circulating endless belts, wherein the welding blade is arranged between the first pair of endless belts and the second pair of endless belts, wherein the first pair of endless belts rotates in a first circulating plane, wherein the welding blade extends longitudinally in a welding blade plane,wherein the first rotational plane and the welding knife plane each run perpendicular to the film plane, wherein the first rotational plane and the welding knife plane intersect each other at an angle, wherein the first pair of circulating endless belts each rotates over at least two first rotational elements, wherein the second pair of circulating endless belts each rotates over at least two second rotational elements, wherein the second pair of circulating endless belts each rotates over at least two second rotational elements, wherein the first rotational elements and the second rotational elements have parallel axes of rotation. A belt guide of each endless belt of the second pair of endless belts runs obliquely to a respective axis of rotation of the at least two second rotational elements, wherein a width of the second pair of endless belts is smaller than a width of the first pair of endless belts,and wherein the longitudinal cutting welding device comprises a drive device, wherein the drive device drives the first pair of endless belts and the second pair of endless belts together.,

[0015] In other words, the proposed arrangement provides for the welding knife to be arranged at an angle to the endless belts of an adjacent film guide. It has been shown that, particularly with large longitudinal extensions of the welding knife, it must be ensured that the film is actually guided along the entire length of the welding knife or cutting-off welding knife parallel to the transport direction of the welding knife or cutting-off welding knife. In this way, heat can be evenly introduced into the films over the entire length of the cutting-off welding knife in order to weld them evenly. An increased longitudinal extension of the welding knife in the transport direction of the upper and lower film webs enables the films to remain on the heated welding knife for a longer time at a constant film transport speed. The heat input can therefore be increased ora consistent heat input can be provided at a lower temperature of the welding knife. A lower temperature of the welding knife makes a significant contribution to improving the quality of the cutting weld seam, as chemical reactions of the plastic in the film webs, for example blistering, burning or smoke development, can be avoided. In use, the longitudinal cutting and welding direction is arranged with regard to the transport direction and the product to be packaged in such a way that the welding knife is aligned parallel to the transport direction and the first rotating plane of the first pair of endless belts is arranged on the side of the welding knife facing away from the product. Viewed in the transport direction, the first rotating plane or the first pair of endless belts runs away from the welding knife. This means that the distance between the welding knife and the first pair of endless belts orthe distance between the welding knife plane and the circulation plane in the transport direction is increased.

[0016] On the one hand, this achieves additional transverse tightening of the film webs. This can be done in addition to or as an alternative to the existing transverse tightening devices. More importantly, however, is that the film is pulled outwards towards the welding knife immediately in front of the welding knife and at the height of the welding knife as seen in the direction of transport. From the perspective of the upper and lower film webs, these are essentially pushed onto the welding knife. This ensures that the upper and lower film webs move sufficiently close to the welding knife over its entire longitudinal extent in the direction of transport, so that heat can be introduced into the upper and lower film webs over the entire longitudinal extent of the welding knife in the direction of transport.

[0017] The welding knife is arranged adjacent to the first pair of endless belts and is fixed to it.

[0018] It has been shown that with this design, all common film materials such as polypropylene, polyethylene or polyolefins in thicknesses from 9 µm to 100 µm can be satisfactorily separated and welded at only low welding blade temperatures.

[0019] Because the welding knife is arranged between the first pair of endless belts and the second pair of endless belts, guidance of the packaged goods can be provided, in particular, by means of the second pair of circulating endless belts on the side of the welding knife facing the packaged goods.

[0020] These rotating elements can be designed as rollers or wheels, for example. In particular, they can be designed as wheels with external teeth. This external toothing can then mesh with the teeth of the endless belts to convey them safely and prevent slippage.

[0021] Thus, it is specifically provided that the entire longitudinal cutting and welding device itself is arranged at an angle to the transport direction. Only the welding blade and the second pair of endless belts are then aligned parallel to the transport direction due to the angled arrangement.

[0022] It can therefore be provided that the belt guide of each endless belt of the second pair of endless belts runs "obliquely" to the respective axis of rotation of the rotating elements. Oblique here means that it does not run at an angle of 90°. It is inclined by the angle to this axis. So if the angle is 1°, for example, the belt guide forms an angle of 89° with the axis of rotation. In this way, the first rotational plane and the second rotational plane can be arranged obliquely to one another by the angle. Furthermore, it is still possible to drive the endless belts of the second pair of endless belts together with the endless belts of the first pair of endless belts. This simply means that the endless belts of the second pair of endless belts engage with the external teeth of the rotating elements at a slight angle. This is, however, tolerable.In principle, such a belt guide can also be provided for the first pair of endless belts. However, due to the narrow width of the second pair of endless belts, a belt guide for the second pair is advantageous.

[0023] In this way, both the first pair of endless belts and the second pair of endless belts can be driven by a single drive device. This makes it possible, in particular, to achieve a consistent transport speed.

[0024] In this way, a wide pair of first endless belts can be provided to ensure secure film guidance. A thin second pair of endless belts can continue to convey the packaged goods and, as desired, can be arranged in the belt guide at an angle to the rotation axes of the respective rotating elements.

[0025] According to a second aspect of the invention, a longitudinal cutting and welding system for a film packaging machine is proposed, wherein the longitudinal cutting and welding system comprises a first and a second longitudinal cutting and welding device, wherein both the first and the second longitudinal cutting and welding device are a longitudinal cutting and welding device according to the first aspect of the invention or one of its embodiments, and wherein the first and the second longitudinal cutting and welding devices are arranged such that their welding measuring planes run parallel to one another, such that the first pair of circulating endless belts of the first longitudinal cutting and welding device is arranged on a side of the welding blade of the first longitudinal cutting and welding device facing away from the second longitudinal cutting and welding device,and the first pair of circulating endless belts of the second longitudinal cutting welding device is arranged on a side of the welding blade of the second longitudinal cutting welding device facing away from the first longitudinal cutting welding device.

[0026] In other words, a longitudinal cutting and welding system for a film packaging machine, in particular a film packaging machine using the series packing principle, can be provided by two longitudinal cutting and welding devices according to the invention, which are arranged in a mirror image of one another or with respect to the transport direction. In this way, both longitudinal sides of the upper and lower film webs are welded in a way that is possible due to the design of the longitudinal cutting and welding device according to the first aspect of the invention or one of its designs. In particular, sufficient transverse tensioning of the upper and lower film webs is achieved by pulling or pushing the film outwards on both longitudinal sides. In this way, it can be made possible, for example, to eliminate the need for additional transverse tensioning devices between a transverse cutting and welding device and the longitudinal cutting and welding device or in the longitudinal cutting and welding system.

[0027] According to a third aspect of the invention, a film packaging machine for packaging a packaged product is provided, comprising at least one longitudinal cutting and welding device according to the first aspect of the invention in one of its embodiments, wherein the film packaging machine conveys the packaged product in a transport direction through the film packaging machine, wherein the film packaging machine has a transverse cutting and welding device upstream of the longitudinal cutting and welding device with respect to the transport direction, and wherein the welding knife plane of the longitudinal cutting and welding device runs parallel to the transport direction.

[0028] According to a fourth aspect of the invention, a film packaging machine for packaging a packaged product is provided, comprising at least one longitudinal cutting and welding system according to the second aspect of the invention in one of its embodiments, wherein the film packaging machine conveys the packaged product in a transport direction and / or an upper and a lower film web in the transport direction through the film packaging machine, wherein the film packaging machine has a transverse cutting and welding device upstream of the longitudinal cutting and welding device with respect to the transport direction, and wherein the welding knife planes of the longitudinal cutting and welding devices of the longitudinal cutting and welding system run parallel to the transport direction.

[0029] The task posed at the beginning is therefore completely solved.

[0030] In a further embodiment of the longitudinal cutting welding device, it can be provided that the second pair of endless belts is each guided in a belt guide in a second circulation plane, wherein the second circulation plane runs parallel to the welding knife plane.

[0031] The second circulation plane therefore also runs at an angle relative to the first circulation plane. The packaged goods can thus continue to be conveyed in one direction. The separating weld seam also runs in the direction of transport.

[0032] In a further embodiment of a longitudinal cutting welding device, the angle can be 0.5° to 3°.

[0033] It has been shown that in this angle range the desired result can be achieved over a wide range of film thicknesses, in particular from 9 µm to 100 µm.

[0034] Furthermore, it can again be provided that the rotating elements are designed as rollers or wheels, in particular with external teeth. In particular, it can also be provided that the first rotating elements and second rotating elements are at least partially identical. In particular, it can be provided, for example, that a rotating element that transmits a drive torque is provided jointly for both the first pair of endless belts and the second pair of endless belts.

[0035] In one embodiment of the longitudinal cutting and welding device, the width of the first pair of endless belts can be 2 to 30 mm. In particular, the width can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 25 mm.

[0036] In a further embodiment of the longitudinal cutting and welding device, it can be provided that the second pair of endless belts runs over at least two rotation elements, and wherein two of the at least two rotation elements are displaceable relative to one another in an operating state.

[0037] In this way, for example, adjustment to different film thicknesses can be made or the endless belts can be supported by springs, so that a film web is securely held in place.

[0038] In a further embodiment of a longitudinal cutting and welding device, it can be provided that the first pair of endless belts each runs over at least three rotation elements, wherein two of the at least three rotation elements are arranged one above the other in an operating state and are displaceable relative to one another.

[0039] Here, too, it can be provided that the endless belts are supported springily over an area in order to rest securely on the film webs.

[0040] According to a further embodiment of a longitudinal cutting and welding device, it can be provided that a film guide path of the first pair of endless belts corresponds to two and a half times to three times a longitudinal extension of the welding knife in the welding knife plane.

[0041] It has been shown that with this dimensioning, a secure film guide can be achieved and the film webs can be pushed safely onto the welding knife.

[0042] In a further embodiment of the longitudinal cutting welding device, it can be provided that a longitudinal extension of the welding knife in the welding knife plane is 40 mm to 70 mm.

[0043] It has been shown that over these distances, even with low temperatures of the welding blade at around 300 degrees, a satisfactory heat input can be achieved at normal film transport speeds.

[0044] In a further embodiment of a longitudinal cutting and welding device, it can be provided that a film guide path of the first pair of endless belts is 120 mm to 200 mm, in particular 160 mm.

[0045] It has been shown that these guide lengths sufficiently ensure that the first pair of endless belts, which are arranged at an angle to the welding knife, can pull or push the films onto the welding knife without damaging them.

[0046] In one embodiment of the longitudinal cutting welding system, it can be provided that the first and the second longitudinal cutting welding device are arranged opposite one another and are mirror-inverted with respect to a center plane between the welding blade planes of the first and the second longitudinal cutting welding device.

[0047] As already described in detail, this allows a satisfactory welding result to be achieved on both sides of the film bag while simultaneously tightening it transversely.

[0048] According to a further embodiment of the film packaging machine, it can be provided that the first circulation plane of the at least one separating and sealing device runs outwards relative to the transport direction.

[0049] In the context of the present application, the terms “top”, “bottom”, “inside” or “outside” are to be understood as referring to directions of application in the direction of transport and in an operating position of the film packaging machine.

[0050] In a further embodiment of the film packaging machine, it can be provided that the first circulation planes of the first and second longitudinal cutting and sealing devices diverge with respect to the transport direction.

[0051] This again ensures that a satisfactory welding result is achieved on both sides while simultaneously tightening the seam.

[0052] In a further embodiment of the film packaging machine, it can be provided that the film packaging machine has at least one pair of pre-tensioning rollers, the unwinding direction of which runs outwards at a pre-tensioning roller angle relative to the transport direction.

[0053] This pre-tensioner roller angle can be between 1 and 5 degrees, in particular it can be 2 degrees, for example.

[0054] Such a pre-tensioning system can still be provided to achieve a certain transverse tension of the film before it enters the first pair of endless belts of the longitudinal cutting and sealing device. However, the longitudinal cutting and sealing device according to the invention essentially eliminates the need for this pair of rollers.

[0055] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0056] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 is a schematic view of an embodiment of a film packaging machine, Fig. 2 a side view of an embodiment of a longitudinal cutting welding device, Fig. 3 a plan view of an embodiment of a longitudinal cutting welding system along a line III-III in Fig. 2, and Fig. 4 a cross-sectional view of an embodiment of a longitudinal cutting welding system along a line IV-IV in Fig. 2; and Fig. 5 an enlarged plan view of an embodiment of a longitudinal cutting welding device.

[0057] Fig. Figure 1 shows a schematic view of a film packaging machine 10. The film packaging machine 10 is used to provide a packaged item 12 with an outer package. For this purpose, the packaged item 12 is moved through the film packaging machine 10 in a transport direction T.

[0058] The packaged product 12 is wrapped by the film packaging machine 10 with an upper film web 14, which is unwound from an upper film feed 15, and a lower film web 16, which is unwound from a lower film feed 17. This type of wrapping corresponds to the principle of a so-called serial packaging machine, so that the present invention will be explained using the example of a film packaging machine 10 designed as a serial packaging machine.

[0059] The upper film web 14 and the lower film web 16 converge in a film plane 18. The packaged goods 12 thus move into the converging upper film web 14 and lower film web 16.

[0060] A transverse tightening device 20 may be provided, in which the film webs 14, 16 are first subjected to transverse tightening. However, the transverse tightening device 20 is not mandatory in this case and can also be omitted.

[0061] A possible embodiment of this transverse tightening device 20 will be explained in more detail with reference to the following figures. The wrapped packaged item 12 with the transversely tightened film webs 14, 16 then reaches a transverse cutting and sealing device 22. The transverse cutting and sealing device 22 welds the film webs 14, 16 together transversely to the transport direction T and at least partially severes the film webs 14, 16, so that the packaged item 12 no longer has contact with the preceding packaged item along the weld seam. The side of the packaged item 12 facing in the transport direction T is thus already welded.

[0062] The packaged goods then pass through a longitudinal cutting and sealing system 24, which is designed to weld the film webs 14, 16 together at the sides of the packaged goods 12 and to cut off any lateral film overhang. Finally, the side of the packaged goods 12 facing opposite the transport direction T is again welded and cut off by the transverse cutting and sealing device 22. This process simultaneously represents the separation and welding of the side of a subsequent packaged goods facing in the transport direction T. The packaged goods 12 are now welded and trimmed on all four sides, so that the packaged goods 12 are completely enclosed in a film wrapping.

[0063] The sequence of the transverse cutting welding device 22, the longitudinal cutting welding system 24, and the transverse tightening device 20 is shown merely as an example in a frequently occurring configuration. The sequence of these devices can also be different; for example, the transverse cutting welding device 22 can be arranged after the longitudinal cutting welding system 24. Elements of the transverse tightening device 20 can also be provided between or in the transverse cutting welding device 22 or the longitudinal cutting welding system 24.

[0064] Typically, this is followed by a shrink tunnel 26, which is heated to a specific temperature and shrinks the film webs 14, 16 onto the packaged goods 12, so that the film webs 14, 16 tightly enclose the packaged goods 12 without any play. The packaging process is then complete.

[0065] The presence of a shrink tunnel 26 depends fundamentally on the packaging requirements. A shrink tunnel 26 is not mandatory, especially for serial packaging machines.

[0066] Furthermore, the film packaging machine 10 typically has adjustment devices 28 to allow the packaging machine 10 to be adjusted to packaged goods of different widths, lengths, and heights. The speed of the packaging process can also be adjusted using the adjustment devices 28. Furthermore, options are provided for adjusting the packaging machine 10 to different film types, which may differ, for example, in thickness, tear resistance, and surface quality.

[0067] Finally, a film return system 30 is generally provided, which collects excess film material separated by the longitudinal cutting and welding system 24 in order to feed it, for example, to a recycling process.

[0068] II denotes a section of the film packaging machine 10, which is shown in Fig. 2 is shown in a detailed view.

[0069] Fig. Figure 2 shows a side view of a longitudinal cutting and welding device 31 according to the invention. The longitudinal cutting and welding device 31 is arranged downstream of the transverse cutting and welding device 22. The transverse tightening device 20 is arranged upstream of the transverse cutting and welding device 22. The transverse tightening device 20 has two pre-tensioning rollers 32, 33 that pull the film webs 14, 16 between them along the film plane 18. The pre-tensioning rollers 32, 33 form a first pre-tensioning roller pair 34. As will be explained below, a rotational axis of the pre-tensioning rollers 32, 33 is angled outward relative to the transport direction T, so that a corresponding transverse tightening is achieved.

[0070] To ensure that the pre-tension rollers 32, 33 securely pull in the film webs 14, 16 and that the film webs 14, 16 do not slip in the pre-tension rollers 32, 33 due to the applied transverse force, the pre-tension rollers 32, 33, for example, have a rubberized surface, whereas the pre-tension roller 33 has a knurled surface, such as a metal. The surface of the wheel 33 then presses into the surface of the wheel 32, ensuring a non-slip grip and hold of the film webs 14, 16.

[0071] Of course, the surface quality of the pre-tension rollers 32, 33 can also be reversed, so that the pre-tension roller 32 has the knurling and the pre-tension roller 33 has the rubberized surface.

[0072] The wheels 32, 33 ensure, in particular, good transverse tensioning for the transverse cutting welding process by means of the transverse cutting welding device 22. Accordingly, a pair of wheels 37 consisting of two pre-tensioning rollers 35, 36 can be provided in the longitudinal cutting welding device 31, which performs the same function as the first pre-tensioning roller pair 34 with the pre-tensioning rollers 32, 33. However, the pre-tensioning roller pair 37 is not mandatory.

[0073] The cross-cutting welding process by means of the cross-cutting welding device 22 is effected by an upper punch 39 and a lower punch 40. The upper punch 39 has a welding blade that is pressed against the lower punch 40 and welds the film webs 14, 16 together, cutting them. For this purpose, the upper punch 39 and the lower punch 40 are moved towards each other so that they meet in the area of ​​the film plane 18. The welding process is generally achieved using a heated cutting blade. As an alternative to the cutting blade, a heated wire can also be used. The wire is not constantly kept at a high temperature, but rather only pulse-heated. The wire can then cool down again with the punches 39, 40 open, which can lead to a better welding result.

[0074] For transporting and securing the film webs 14, 16, two endless belts 42, 44 are provided in the longitudinal cutting and sealing device. These belts pull and clamp the film webs 14, 16 between them in the film plane 18 and convey the film webs 14, 16 and the packaged goods 12. Thus, one endless belt 42, 44 is arranged on each side of the film plane 18.

[0075] In the example shown, the endless belt 42 runs around three rollers 46, 48, 49. The endless belt 44 runs around three rollers 51, 53, 54.

[0076] The tracks of rollers 46 and 47, as well as rollers 51 and 52, have the same diameter. However, in the area of ​​the endless belt 42, rollers 47 and 52 can have a smaller diameter again, so that the endless belts 42, 44 do not run over the rollers 47 and 52.

[0077] Rollers 48 and 53 are located at the point where the film webs 14, 16 are pulled between them by the endless belts 42, 44. Rollers 49 and 54 are provided vertically offset from the rollers 48 and 53. The rollers 48 and 49, or 53 and 54, are movable relative to one another, for example, by securing the rollers 49 and 54 in a vertically extending slot (not shown). In this way, the tension of the endless belts 42, 44 can be regulated, and in particular, easy replacement of the endless belts 42, 44 can be achieved.

[0078] The film webs 14, 16 are conveyed along the film plane 18 by the endless belts 42, 44 and guided through a welding knife 56. In the example shown, the welding knife 56 is a stationary welding knife, but in principle, a rotating welding knife can also be provided. The welding knife 56 is heated by a suitable device so that the welding knife 56 cuts through the film webs 14, 16 and melts or welds them together at their ends.

[0079] In order to feed the film webs 14, 16 to the welding knife 56 with as few creases as possible, a tension roller 58 is provided in front of the welding knife 56. This tension roller 58 is arranged on the side of the film plane 18 opposite the welding knife 56 and penetrates it. The tension roller 58 briefly lifts the film webs 14, 16 and pulls them largely free of creases. Even if a crease cannot be removed by the tension roller 58, this at least ensures that the other film web 14, 16 also fits into the fold accordingly, so that the film webs 14, 16 lie on top of one another without any air pockets when they are welded. This ensures the quality of a high-quality weld seam.

[0080] Furthermore, a support rail 60 is provided, which is intended to press the film webs 14, 16 firmly and smoothly against one another in the area of ​​the welding knife 56. The contact force of the support rail 60 is generated by means of suitable spring elements 62, 64. These press the support rail 60 onto an opposite support rail 66. The support rails 60, 66 have a Fig. 2 has a recess 68, indicated only by a dashed line, in which the welding blade 56 is arranged. The recess 68 will be described in more detail with reference to the following figures.

[0081] Fig. 3 shows a top view along the line III-III in Fig. 2 designated slide level 18.

[0082] The film packaging machine described in this exemplary embodiment is a so-called series packaging machine. Accordingly, two longitudinal sides 69 of the packaged product 12 are sealed by means of a corresponding longitudinal cutting and sealing device 31. Thus, the longitudinal cutting and sealing system 24 comprises two longitudinal cutting and sealing devices 31, 31', which are arranged opposite one another and are constructed in a mirror-image manner. Consequently, only one of the two longitudinal cutting and sealing devices 31 will be explained in more detail; reference numerals of the opposite longitudinal cutting and sealing device 31 are truncated with a prime.

[0083] The view in Fig. 3 shows a pre-tension roller angle 70 by which the running directions of the pre-tension rollers 33 and 36 are inclined outwards relative to the transport direction T.

[0084] The welding knife 56 cuts the film webs 14, 16 along the respective longitudinal side 69, 69'. This creates a waste strip 71, which is conveyed by the endless belts 42, 44. This waste strip 71 is fed to the film return line 30.

[0085] Furthermore, a second endless belt 72 is arranged on the side of the welding blade 56 facing the packaged goods 12. This endless belt 72 is significantly narrower than the endless belt 44; in particular, it can have a width of 2 mm to 30 mm, in particular of approximately 3 mm.

[0086] Thus, the film webs 14, 16 are pressed together, guided and transported in the area of ​​the welding knife 56 on both sides of the welding knife.

[0087] The endless belt 72 runs over an auxiliary roller 73 and the roller 52. The auxiliary roller 73 runs concentrically to the roller 51.

[0088] Furthermore, a holding element 74 is provided to hold the rollers 51, 73, 52, 53, 54 and the corresponding roller elements present on the opposite side of the film plane 18.

[0089] The endless belt 44 and the endless belt 72 form a longitudinal gap 75 between them, in which the welding blade 56 and the tensioning roller 58 are arranged. Extending from the support element 74 are several support shafts 76 (not individually numbered), each of which has a corresponding length to support the roller elements 51, 52, 53, 54, 73, the welding blade 56, and the tensioning roller 58 at corresponding distances from one another, forming the longitudinal gap 75.

[0090] Furthermore, the Fig. 3 that the longitudinal cutting and sealing devices 31, 31' diverge outwards with respect to the transport direction. However, due to the arrangement of the welding blades 56 and 56' and the respective second pair of endless belts 72, 72', these are arranged parallel to the transport direction. The packaged goods 12 are therefore still guided in the transport direction, just as the films 14, 16 are ultimately guided. The cutting and sealing seams are also created parallel to the transport direction T. As the films pass through the longitudinal cutting and sealing device 31, 31', the inclined position of the first pair of endless belts ensures that the films are stretched transversely and that they rest securely over the entire longitudinal extent of the welding blades 56, 56' in the transport direction. In particular, for this reason, the transverse tightening devices in the form of the pre-tensioning roller 36 can be dispensed with.

[0091] The exact arrangement of the longitudinal cutting welding device 31, 31' is determined in connection with the Fig. 5 explained in more detail.

[0092] Fig. 4 shows a cross-sectional view along the line IV-IV in Fig. 2. Pictured in Fig. 4 is the longitudinal cutting and welding system 24 with the two longitudinal cutting and welding devices 31, viewed in the transport direction T.

[0093] With regard to the endless belts 42, 44, it can be seen in this view that they are guided on the rollers 46 and 51, respectively, of a corresponding groove 77 and 77', respectively. The groove has a U-shaped cross-sectional profile, so that the legs of the U provide a lateral guide 78 and 78', respectively, on both sides of the corresponding belt 42, 44. This prevents the corresponding endless belt 42, 44 from slipping sideways off the respective roller guide. A corresponding belt guide 84 is provided for the endless belts 72, 79.

[0094] The Fig. 5 shows an enlarged plan view of a longitudinal cutting and welding device. In this enlarged plan view, the effects of implementing the angle 76 can be seen in particular. The first pair of endless belts, of which the endless belt 42 is schematically shown using the first rotational plane 78, is arranged at an angle 76 to both the welding blade 56 or the welding blade plane 82 and the second rotational plane 80 of the second pair of endless belts, of which only the endless belt 72 is shown. It can be seen that the first rotational plane still runs perpendicular to the axes of rotation of the rotation elements and the drive device 90. The axes of rotation 86, 88 are thus perpendicular to the first rotational plane 78. These are therefore arranged overall at an angle to the transport direction T. However, the angle 76 means that the welding blade 56 orthe welding knife plane 82 and the second circulation plane 80 parallel to the transport direction T. In this way, the film webs are pulled outwards by the first pair of endless belts 42, that is to say in the . Fig. 5 are pulled to the right and, so to speak, pushed onto the welding knife 56, and in this way they maintain a sufficiently small distance from the welding knife 50 over the longitudinal extent 96 thereof, so that heat can be introduced. The entire film guide, i.e. the area in which the endless belts 42 of the first pair of endless belts clamp the film web 14, 16 between them, is designated by 98. In particular, this area can be two and a half times to three times as long as the longitudinal extent 96 of the welding knife. A width 94 of the endless belts 42 of the first pair of endless belts is wider than a width 92 of the endless belts 72 of the second pair of endless belts. For example, it can be provided that the width 94 of the first pair of endless belts corresponds to approximately 25 mm and the width 92 of the second pair of endless belts corresponds to 6 mm.

[0095] It can be seen that the belt guide 84 of the belt 72 of the second pair of endless belts ultimately forces it into the inclined position. The rotation elements 51 or the external toothings that guide and drive the belt 72 are designed parallel to the rotation axes 86, 88. Due to the inclined belt guide 84, the belt is forced into the inclined running direction. This has the result that, as shown in the Fig. 5 shows that the belt 72 is only partially engaged with the outer teeth at a slight angle. However, this is tolerable due to the relatively small angle 76.

[0096] In this way, it is possible to drive belts 42 and 72 together. No further complex structural modifications to the longitudinal cutting and welding device 31 are required compared to the known, simple design.

Claims

[1] Longitudinal cutting and welding device (31) for a longitudinal cutting and welding system (24) of a film packaging machine (10), wherein the longitudinal cutting and welding device (31) has a first pair of endless belts (42, 44), wherein the first pair of endless belts (42, 44) is designed to pull an upper (14) and a lower (16) film web between them and to guide them in a film plane (18), and wherein the longitudinal cutting and welding device (31) further has a welding knife (56) for longitudinally cutting and welding the upper (14) and the lower (16) film web, wherein the longitudinal cutting and welding device (31) has a second pair of circulating endless belts (72, 79), wherein the welding knife (56) is arranged between the first pair of endless belts (42, 44) and the second pair of endless belts (72, 79), wherein the first pair of circulating endless belts (42, 44) each have at least two first rotation elements (46, 48, 49;51, 53, 54), wherein the second pair of circulating endless belts (72, 79) each rotates over at least two second rotation elements (47, 46; 51, 52), wherein the first rotation elements (46, 48, 49; 51, 53, 54) and the second rotation elements (47, 46; 51, 52) have parallel axes of rotation (86, 88), wherein the first pair of endless belts (42, 44) rotates in a first rotation plane (78), wherein the welding knife (56) extends longitudinally in a welding knife plane (56), wherein the first rotation plane (78) and the welding knife plane each run perpendicular to the film plane (18), ; characterized byin that the first circumferential plane (78) and the welding knife plane (56) intersect one another at an angle (76), wherein the belt guide (84) of each endless belt (72, 79) of the second pair of endless belts (72, 79) runs obliquely to a respective axis of rotation of the respective at least two second rotation elements (47, 46; 51, 52), wherein a width (92) of the second pair of endless belts (72, 79) is smaller than a width (94) of the first pair of endless belts (42, 44), and wherein the longitudinal cutting welding device (31) has a drive device (90), wherein the drive device (90) drives the first pair of endless belts (42, 44) and the second pair of endless belts (72, 79) jointly. [2] Longitudinal cutting welding device according to claim 1, characterized by that the second pair of endless belts (72, 79) are each guided in a belt guide (84) in a second circular plane (80), wherein the second circular plane (80) runs parallel to the welding knife plane (56). [3] Longitudinal cutting welding device according to claim 1 or 2, characterized by that the angle (76) is 0.5° to 3.0°. [4] Longitudinal cutting welding device according to one of claims 1 to 3, characterized by that a width (94) of the first pair of endless belts (42, 44) is 2 to 30 mm. [5] Longitudinal cutting welding device according to one of claims 2 to 4, characterized by that the second pair of endless belts (72, 79) each runs over at least two rotation elements (47, 46; 51, 52), and wherein two of the at least two rotation elements (47, 46; 51, 52) are displaceable relative to one another in an operating state. [6] Longitudinal cutting welding device according to one of claims 1 to 5, characterized byin that the first pair of endless belts (42, 49) each runs over at least three rotation elements (46, 48, 49; 51, 53, 54), wherein two (48, 49; 53, 54) of the at least three rotation elements (46, 48, 49; 51, 53, 54) are arranged one above the other in an operating state and are displaceable relative to one another. [7] Longitudinal cutting welding device according to one of claims 1 to 6, characterized by that a film guide path of the first pair of endless belts (42, 49) corresponds to two and a half times to three times a longitudinal extension (96) of the welding knife (56) in the welding knife plane (82). [8] Longitudinal cutting welding device according to one of claims 1 to 7, characterized by that a longitudinal extension (96) of the welding knife (56) in the welding measuring plane is 40 mm to 70 mm. [9] Longitudinal cutting welding device according to one of claims 1 to 8, characterized bythat a film guide path (98) of the first pair of endless belts (42, 49) is 120 mm to 200 mm, in particular 160 mm. [10] Longitudinal cutting and sealing system (24) for a film packaging machine (10), characterized bya first and a second longitudinal cutting welding device (31, 31'), wherein both the first and the second longitudinal cutting welding device (31, 31') are longitudinal cutting welding devices according to one of claims 1 to 9, and wherein the first and the second longitudinal cutting welding devices are arranged such that their welding knife planes run parallel to one another, that the first pair of circulating endless belts (42, 44) of the first longitudinal cutting welding device (31) is arranged on a side of the welding knife (56) of the first longitudinal cutting welding device (31) facing away from the second longitudinal cutting welding device (31), and that the first pair of circulating endless belts (42, 44) of the second longitudinal cutting welding device (31) is arranged on a side of the welding knife (56) of the second longitudinal cutting welding device (31) facing away from the first longitudinal cutting welding device (31). [11] Longitudinal cutting welding system according to claim 10, characterized bythat the first and second longitudinal cutting welding devices (31, 31') are arranged opposite one another and are mirror-inverted with respect to a center plane between the welding blade planes (56) of the first and second longitudinal cutting welding devices (31, 31'). [12] Film packaging machine (10) for packaging a packaged product, with at least one longitudinal cutting and welding device (31) according to one of claims 1 to 9, wherein the film packaging machine (10) conveys the packaged product in a transport direction (T) through the film packaging machine (10), wherein the film packaging machine (10) has a transverse cutting and welding device (22) upstream of the longitudinal cutting and welding device (31) with respect to the transport direction (T), and wherein the welding knife plane (56) of the longitudinal cutting and welding device (31) runs parallel to the transport direction (T). [13] Film packaging machine (10) according to claim 12, characterized bythat the first rotation plane (78) of the at least one longitudinal cutting and welding device (31, 31') runs outwards relative to the transport direction (T). [14] Film packaging machine (10) for packaging a packaged product, with at least one longitudinal separation and welding system (24) according to claim 10 or 11, wherein the film packaging machine (10) conveys the packaged product in a transport direction (T) through the film packaging machine (10), wherein the film packaging machine (10) has a transverse separation and welding device (22) upstream of the longitudinal separation and welding device (31) with respect to the transport direction (T), and wherein the welding knife planes (56) of the longitudinal separation and welding devices (31, 31') of the longitudinal separation and welding system (24) run parallel to the transport direction (T). [15] Film packaging machine (10) according to claim 14, characterized bythat the first circulation planes (78) of the first and second longitudinal cutting and welding devices (31, 31') diverge with respect to the transport direction (T). [16] Film packaging machine (10) according to one of claims 12 to 15, characterized by that the film packaging machine (10) has at least one pair of pre-tensioning rollers (32, 34; 35, 36) whose unwinding direction runs outwards at a pre-tensioning roller angle (70) relative to the transport direction (T).

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