Longitudinal cutting and sealing device, longitudinal cutting and sealing system, packaging machine and process

Abstract

The present invention relates to a longitudinal cutting and welding device (22) for cutting and welding an upper material web (14) and a lower material web (16), wherein the longitudinal cutting and welding device (22) has at least a first pair of circulating endless elements (134, 136; 144, 146) for drawing the first and second material webs (14, 16) between them and guiding the first and second material webs (14, 16) in a material web plane (19) in a transport direction (T), wherein the longitudinal cutting and welding device (22) has a welding device (127), wherein the welding device (127) has a heatable welding wheel (120) and a first pressing assembly (125) for pressing the material webs (14, 16) against the welding wheel (120), wherein the first pressing assembly (125) has a first pressing wheel (122, 124), wherein the welding device (127) comprises a heating block,which is arranged on a side opposite the welding wheel (120) with respect to the material web plane (19) and in front of the welding wheel (120) with respect to the transport direction, wherein the welding device (127) has a second pressing assembly for pressing the material webs (14, 16) against the heating block, wherein the second pressing assembly (125) has at least one second pressing wheel.

Description

[0001] The present invention relates to a packaging machine for packaging a packaged product with an outer packaging produced from an upper paper web and a lower paper web and to a method for controlling a packaging machine.

[0002] Packaging machines are used in many industrial applications for packaging a variety of goods. These goods can be consumer goods such as data storage devices, books, or standard supermarket items, as well as specialty items such as spare parts or building materials like clay. Packaging machines are also regularly used for magazines with inserts or in the mail-order sector.

[0003] The present invention primarily concerns packaging machines, which are generally divided into form-shoulder machines, serial packing machines, and banding machines. While form-shoulder machines and serial packing machines are designed to completely wrap a packaged product, a banding machine merely places a band around the packaged product.

[0004] All packaging machines have in common that the outer packaging must be sealed and cut on at least one side. For banderoles, this is usually only the case on one side, for form-shoulder machines on two or three sides, and for serial packaging machines on all four sides of the packaged goods. Therefore, packaging machines always have a so-called transverse cutting device, which seals and at least partially cuts the outer packaging transversely to the transport direction of the packaged goods in the packaging machine. Furthermore, packaging machines have longitudinal sealing devices or longitudinal cutting devices, which seal the outer packaging parallel to the transport direction of the packaged goods and cut off any excess packaging material.

[0005] For the purposes of the present invention, "packaging machine" refers to all of the aforementioned types of packaging machines, but the present invention particularly concerns serial packaging machines. One such serial packaging machine is shown, for example, in document DE 10 2006 001 594 A1.

[0006] In packaging machines, it is known that the packaging material forming the outer packaging is, for example, plastic film, e.g., made of polyethylene, polyolefin, or the like. Despite the increasing degree of recyclability, such plastic packaging can have a negative impact on the environment. In the field of packaging technology, particularly in the mail-order sector, the use of paper for packaging goods is therefore becoming increasingly important. An example of outer packaging made of paper can be found in the publication DE 20 2019 105 885 U1.

[0007] The document DE 20 2016 005 970 U1 relates to a welding device, in particular as part of a packaging machine for packaging objects, for a continuous packaging film which, with an upper film layer and a lower film layer, substantially projects over and / or envelops objects and can be welded to the two film layers by the welding device on at least one long side in the direction of travel.The welding device has a rotating, heatable welding wheel for welding the film layers and at least one rotating counter-contact means which bears against the welding wheel in a contact area, wherein the counter-contact means is a rotating belt with a support against the welding wheel, wherein the support has at least one pressure wheel, and wherein the support is arranged so close to the contact area of ​​the welding wheel on the belt that a distance from the support to the contact area lies within the width of the projection of the welding wheel on the belt.

[0008] Compared to plastic films, which are regularly used to produce outer packaging in conventional film packaging machines, the processing of paper is significantly more complex due to its relatively low resistance to stress cracking and its high susceptibility to cracking. For example, the film webs of conventional film packaging machines are exposed to high tensile and shear loads during the conveying process, longitudinal cutting and / or transverse cutting and welding processes. It has been shown that simply retrofitting conventional film packaging machines with paper webs instead of film webs is not effective due to the aforementioned susceptibility to cracking of paper.

[0009] From the document DE 10 2020 106 030 A1, a longitudinal cutting and welding device for cutting and welding an upper paper web and a lower paper web is known, wherein the longitudinal cutting and welding device has at least a first pair of rotating endless elements which pull the first and the second paper web between them and guide them in a paper web plane, wherein the longitudinal cutting and welding device has a welding device, wherein the welding device has a heatable welding wheel for welding the paper webs and a pressing assembly for supporting the paper webs against the welding wheel, wherein the pressing assembly has at least one pressing wheel, in particular exactly two pressing wheels, wherein the welding wheel is adjustable between a working position in which the pressing assembly rests against the welding wheel, and a rest position in which the welding wheel is spaced from the pressing assembly,and wherein the welding device has at least one biasing element which biases the welding wheel into the rest position.,

[0010] Document WO 2021 / 074194 A1 discloses a packaging device for heat-sealing packages, comprising a vacuum chamber having an elongated opening extending along or parallel to a longitudinal axis of the vacuum chamber, and a conveyor belt configured to receive semi-sealed packages and to move the semi-sealed packages relative to the vacuum chamber along a main movement direction, such that each semi-sealed package positioned on the conveyor belt can have an end portion passing through the elongated opening during the relative movement of the semi-sealed package with respect to the vacuum chamber, with its opening moving relatively inside the vacuum chamber while the main portion moves relatively outside the vacuum chamber.The packaging apparatus further includes an evacuation device in fluid communication with the vacuum chamber for evacuating gas present in the semi-sealed packages and forming evacuated semi-sealed packages. The packaging apparatus further includes a heat-sealing device configured to heat-seal the terminal portion of each evacuated semi-sealed package, thereby forming heat-sealed packages.

[0011] It is an object of the present invention to provide an improved longitudinal cutting and sealing device, a longitudinal cutting and sealing system, a packaging machine and a method for packaging which provides an improved cutting and sealing result for the cutting and sealing of material webs made of both paper and plastic.

[0012] A longitudinal cutting and welding device is therefore proposed for cutting and welding an upper material web and a lower material web, wherein the longitudinal cutting and welding device has at least a first pair of rotating endless elements for drawing the first and second material webs between them and guiding the first and second material webs in a material web plane in a transport direction, wherein the longitudinal cutting and welding device has a welding device, wherein the welding device has a heatable welding wheel and a first pressing assembly for pressing the material webs against the welding wheel, wherein the first pressing assembly has a first pressing wheel, wherein the welding device has a heating block which is arranged on a side opposite the welding wheel with respect to the material web plane and in front of the welding wheel with respect to the transport direction,wherein the welding device comprises a second pressing assembly for pressing the material webs against the heating block, wherein the second pressing assembly comprises at least one second pressing wheel.

[0013] The term “material web” in this context refers to a layer of packaging material made from a single material, whereby the material can be a paper web or a plastic film or plastic film web. Paper as a material can also be paper-like material made from materials other than wood-based fiber, but which has properties suitable for packaging, such as strength, foldability, or the like. In principle, however, hybrid packaging materials, e.g. paper / plastic composites or the like, are also included. It goes without saying that, in the case of paper as the material, the upper and lower material webs are each at least partially coated on the inner surfaces facing one another in order to enable thermal sealing or welding of the superimposed material webs.

[0014] The term "endless element" refers to a self-contained, particularly belt-shaped, drive element for conveying material webs, which can be designed, for example, as a belt, chain, and / or the like. Such endless elements are particularly well suited for conveying material webs due to their flat load distribution.

[0015] The term "material web level" refers to the level at which the upper material web and the lower material web converge and are transported and processed by the packaging machine. The material web level can, for example, be the level at which the transport device for transporting the packaged goods is located; however, the material web level can also be located approximately halfway up the packaged goods, for example.

[0016] The term "heating block" refers to an element made of a solid material. This element is heated to a heating temperature. Conventional configurations such as a heating cartridge can be used for heating. The heating block then transfers the heat to the superimposed material webs passing through it.

[0017] For the purposes of this description, the terms "longitudinal cutting and welding device" and "transverse cutting and welding device" are also used, which are commonly used in the processing of films. Accordingly, the term "welding" is generally used. In the case of plastic as the material, the webs are glued, fused, or sealed together by the application of heat. In the case of paper as the material, the webs are usually coated, for example, with an adhesive and / or a plastic. The material webs are thus bonded to one another by the application of heat to the adhesive and / or the plastic. Instead of the term "welding" or "welding," the terms "gluing" or "adhering" or "sealing together" could also be used.Accordingly, instead of “longitudinal cutting and welding device” and “transverse cutting and welding device”, one could also speak of “longitudinal cutting and bonding device” and “transverse cutting and bonding device” or of “longitudinal cutting and sealing device” and “transverse cutting and sealing device”.

[0018] Using the heating block, it is possible to extend the distance of heat input into the overlapping material webs without necessarily having to guide the material webs through a large angular range of the welding wheel. The material webs are guided along the heating block in a straight path without shifting against each other. At this distance, a significant amount of heat is already being input into the material webs, heating them up and beginning to fuse them together. The angular range over which the material webs are then guided along the pressure wheel can thus be shortened. In particular, a single pressure wheel, which presses the material webs against the welding wheel, may then be sufficient.In particular, it is no longer absolutely necessary for the material webs to take a strong "S-shaped" course and for the welding wheel to extend downwards far beyond the plane of the material web in order to increase the angular range in which the material webs rest against the welding wheel. The curve that the material webs take around the welding wheel and between the welding wheel and the pressure wheel is still there, but very short and thus keeps the displacement in the material web relative to one another small. With a large angular range and a correspondingly long arc distance over the outer radius of the pressure wheel, the arc distance is long and correspondingly the displacement of the material webs relative to one another is relatively large because the radially inner material web had to travel a relatively shorter distance than the outer material web. This could lead to the formation of wrinkles.Due to the very short arc distance, the formation of wrinkles can now be avoided. A final pressing of the material webs takes place between the welding wheel and the pressure wheel. The material webs have already been heated along the heating block to such an extent that a secure weld is now achieved.

[0019] According to a further aspect, a longitudinal cutting and welding system is provided with a first and a second longitudinal cutting and welding device for welding the material webs parallel to the transport direction on two opposite longitudinal sides of the material webs, wherein both the first longitudinal cutting and welding device and the second longitudinal cutting and welding device are longitudinal cutting and welding devices according to the first aspect of the invention or one of its embodiments, wherein the first and the second longitudinal cutting and welding device each have at least the first pair of circulating endless elements which pull the first and the second material web between them on the two opposite longitudinal sides of the material webs and guide them in a material web plane.

[0020] According to yet another aspect, a packaging machine for packaging a packaged product with an outer packaging produced from an upper material web and a lower material web, wherein the packaging machine has a longitudinal separation and welding system according to the invention.

[0021] Furthermore, according to one aspect, a method is provided for longitudinally separating and welding an upper and a lower material web, comprising the steps of providing a longitudinal separating and welding device, at least a first pair of circulating endless elements for drawing the first and second material webs between them and guiding the first and second material webs in a material web plane in a transport direction, wherein the longitudinal separating and welding device comprises a welding device, wherein the welding device comprises a heatable welding wheel and a first pressing assembly for pressing the material webs against the welding wheel, wherein the first pressing assembly comprises a first pressing wheel, wherein the welding device comprises a heating block which is arranged on a side opposite the welding wheel with respect to the material web plane and in front of the welding wheel with respect to the transport direction,wherein the welding device comprises a second pressing assembly for pressing the material webs, in particular against the heating block or the heat-conducting strip, wherein the second pressing assembly comprises at least one second pressing wheel; and conveying the upper material web and the lower material web through the longitudinal cutting and welding device by means of the at least one first pair of rotating endless elements, wherein the first and second material webs are first conveyed along the heating block and then conveyed over the welding wheel at least at one contact point.

[0022] The advantages according to the invention can also be provided by a method in this way.

[0023] The task posed at the beginning is thus completely solved.

[0024] In one embodiment of the longitudinal cutting and welding device, it can be provided that the first pressure assembly has exactly one first pressure wheel.

[0025] By providing exactly one first pressure wheel, sufficient contact of the welding wheel with the material webs can be ensured on the one hand, and an excessively large bend in the guidance of the material webs can be avoided on the other hand.

[0026] In one embodiment of the longitudinal cutting welding device, it can be provided that the welding wheel is adjustable between a working position in which the first pressure assembly rests against the welding wheel and a rest position in which the welding wheel is spaced from the first pressure assembly, and wherein the welding device has at least one first pretensioning element which pretensions the welding wheel into the rest position.

[0027] This ensures that if the material webs stop, the rest position can be assumed, thus preventing excessive heating of the material webs. Excessive heating of the material webs can cause damage to the material webs or even burn them through, resulting in time-consuming restarting. However, in the rest position, there is sufficient distance between the welding wheel and the material webs, interrupting further heat input into the material webs. Stopping of the material webs can occur intentionally in the case of cyclical operation or can occur unintentionally in the case of an emergency stop or an interruption in the power supply.

[0028] In one embodiment of the longitudinal cutting and welding device, it can be provided that the heating block is adjustable between a working position in which the second pressure assembly rests against the heating block and a rest position in which the heating block is spaced apart from the pressure assembly, and wherein the welding device has at least one second prestressing element which prestresses the heating block into the rest position.

[0029] This ensures that if the material webs are stopped, the heating block can also return to its rest position, thus preventing excessive heating of the material webs. In the rest position, there is then sufficient clearance between the heating block and the material webs, preventing any further heat transfer into the material webs, possibly through the heat-conducting tape.

[0030] In one embodiment of the longitudinal cutting and welding device, it can be provided that the welding device further comprises a circumferential heat-conducting band which is arranged such that it circulates around at least the heating block between the heating block and the lower material web.

[0031] The thermally conductive tape can protect the lower material web. Without the thermally conductive tape, the lower material web would drag over the thermally conductive block, which could cause damage or even tearing. The circumferential thermally conductive tape ensures that there is virtually no friction between the lower material web and the thermally conductive tape. In particular, the thermally conductive tape rotates at the transport speed of the material webs.

[0032] In one embodiment of the longitudinal cutting and welding device, it can be provided that the heat-conducting band is made of a metal or of polytetrafluoroethylene.

[0033] This choice of material ensures that heat transfer from the heating block to the material webs through the thermal tape can occur smoothly due to the material's thermal conductivity. At the same time, the coefficient of friction is sufficiently low and the mechanical strength is sufficiently high.

[0034] In one embodiment of the longitudinal cutting and welding device, it can be provided that the longitudinal cutting and welding device further comprises a drive device for driving the heat-conducting strip.

[0035] In this way, the thermal tape can be driven at the desired feed rate independently of the other components.

[0036] In one embodiment of the longitudinal cutting and welding device, it can be provided that the longitudinal cutting and welding device further comprises a tensioning device in order to tension the heat-conducting band, in particular in order to compensate for a temperature-related expansion of the heat-conducting band.

[0037] The thermal tape is heated by the heating block. Due to its length and its coefficient of thermal expansion, the thermal tape then expands. The tensioning device compensates for this expansion and ensures that the surrounding thermal tape remains taut.

[0038] In one embodiment of the longitudinal cutting and welding device, it can be provided that the superimposed material webs, in particular in the working position, rest on the welding wheel in at least one contact point, in particular in a contact area.

[0039] This ensures that the material webs are pressed together and securely welded under heat input.

[0040] In one embodiment of the longitudinal cutting welding device, it can be provided that the welding wheel and the first pressure wheel of the first pressure assembly are driven jointly or are arranged to be free-running.

[0041] The welding wheel can be designed as a rotating, heatable welding wheel. The at least one first pressure wheel is also designed to rotate. An advantage of this design is that the material webs are transported through the respective welding device without slippage. In this way, the material webs are not pulled by the welding devices, unlike with stationary welding and pressure wheels, resulting in comparatively less wear as the material webs pass through the welding devices.

[0042] In one embodiment of the longitudinal cutting and welding device, it can be provided that the at least one second pressure wheel of the second pressure assembly is driven.

[0043] In this way, any friction on the upper material web can be reliably avoided. Preferably, the at least one second pressure wheel is driven at the same speed as the rotating heat-conducting belt.

[0044] In one embodiment of the longitudinal cutting welding device, it can be provided that an outer circumference of the welding wheel extends through the material web plane.

[0045] An advantage of this design is that, compared to a situation in which the outer circumference of the welding wheel does not extend through the plane of the material web, an extended contact area is created, larger than at a single point, thus improving heat transfer to the material webs. The angular range of the wrap can be kept small with only a single first pressure wheel, for example, less than 20°, especially less than 10°. In particular, the area in which the superimposed material webs curve together can be kept small, thus preventing unwanted wrinkling.

[0046] In one embodiment of the longitudinal cutting and welding device, it can be provided that the longitudinal cutting and welding device further comprises a longitudinal cutting device for cutting the superimposed material webs parallel to the transport direction, wherein the longitudinal cutting device comprises a rotating circular blade and a support wheel for supporting the material webs against the circular blade.

[0047] In one embodiment of the longitudinal cutting and welding device, it can be provided that the circular blade and the support wheel are driven together.

[0048] It can be provided that the circular blades and the support wheel are driven, for example, by a drive device. In principle, a drive device different from the other drive devices is conceivable. Alternatively, it can be provided that only the circular blade is driven, while the support wheel is designed to be free-running.

[0049] In one embodiment of the longitudinal cutting and welding device, it can be provided that the longitudinal cutting and welding device further comprises at least one second pair of circulating endless elements which pull the superimposed material webs between them on the two opposite longitudinal sides of the material webs and guide them in the material web plane, wherein the circular knife is arranged in the material web plane orthogonal to the transport direction between the first pair of endless elements of the respective longitudinal cutting and welding device and the second pair of endless elements of the same longitudinal cutting and welding device.

[0050] In other words, in the respective longitudinal cutting and sealing device, the circular blade is arranged between the first pair of endless elements and the second pair of endless elements in such a way that the material webs are guided in the transport direction by the first and second pair of endless elements on the side of the circular blade facing the packaged goods and on the opposite side of the circular blade facing away from the packaged goods.

[0051] In one embodiment of the longitudinal cutting and welding device, it can be provided that the second pair of endless elements of the longitudinal cutting and welding devices each rotate in a second rotation plane, wherein the second rotation plane runs parallel to the circular blade plane.

[0052] It has been shown that parallel guidance of the material webs using spaced-apart pairs of endless elements in the respective longitudinal cutting and welding device is preferable to guidance of the material webs inclined transversely outwards. In particular, the parallel guidance can prevent potential crack propagation upstream of the respective longitudinal cutting device, which could otherwise occur due to transverse tightening. Alternatively, however, the second rotating plane can also be inclined relative to the circular blade plane in order to cut off any lateral material overhang.

[0053] In one embodiment of the longitudinal cutting and welding device, it can be provided that the first and the second longitudinal cutting and welding device each have a pair of rollers arranged downstream of the first and / or second pairs of endless elements in the transport direction, wherein the respective pair of rollers of the longitudinal cutting and welding devices is designed to pull the two material webs between them and to guide them in the material web plane, wherein the rollers of the respective pair of rollers run outwards at a pre-tensioning roller angle relative to the transport direction, in particular in such a way that a material overhang laterally severed by means of the longitudinal cutting device is transported away by the pair of rollers of the respective longitudinal cutting and welding device.

[0054] This ensures that the cut-off excess material runs outward relative to the transport direction. However, this is merely an optional feature, particularly suitable when the first and second rotation planes are arranged parallel to the circular blade plane.

[0055] In one embodiment of the longitudinal cutting and welding device, it can be provided that the longitudinal cutting device is arranged behind the welding device in the transport direction.

[0056] Accordingly, the overlapping material webs are first welded longitudinally in the transport direction and then fed to the longitudinal cutting device for severing the overlapping material web sections parallel to the transport direction on two opposite longitudinal sides of the outer packaging. However, it is also possible to arrange the longitudinal cutting devices next to or upstream of the welding devices in the transport direction.

[0057] It is understood that the features mentioned above and those yet 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.

[0058] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 a schematic side view of a packaging machine; Fig. 2 a side view of an embodiment of a longitudinal cutting welding device; Fig. 3 an isometric view of the longitudinal cutting welding device; Fig. 4 a plan view of the longitudinal cutting and welding device; Fig. 5 an isometric view of the welding wheel and the first pressure wheel; and Fig. 6 schematic flow diagram of a method for operating a packaging machine.

[0059] Fig. Figure 1 shows a schematic view of a packaging machine 10. The packaging machine 10 is used to provide a packaged item 12 with an outer package. For this purpose, the packaged item 12 is transported through the packaging machine 10 in a transport direction T.

[0060] The packaged goods are wrapped by the packaging machine 10 with an upper material web 14, which is unwound from an upper supply or unwinding roll 15, and a lower material web 16, which is unwound from a lower supply or unwinding roll 17. This type of wrapping corresponds to the principle of the serial packaging machine. The upper material web 14 and the lower material web 16 are fed by means of a first feed device 18 and a second feed device 18'.

[0061] The upper material web 14 and the lower material web 16 converge in a material web plane 19, in which they are conveyed and processed by the packaging machine 10. The material webs 14, 16 are preferably inclined relative to one another. The material web plane 19 can be the plane in which, for example, a transport device for transporting the packaged goods is arranged. However, the material web plane can also be provided, for example, at approximately half the height of the packaged goods 12, as shown with a material web plane 19'. In particular, the height of the material web plane 19 can be adjustable. The packaged goods 12 thus move into the converging upper material web 14 and lower material web 16.

[0062] The wrapped packaged goods 12 reach a cross-cutting welding device 20. The cross-cutting welding device 20 closes the material webs 14, 16 together transversely to the transport direction and at least partially cuts through the material webs 14, 16, so that the packaged goods 12 no longer has any contact with the packaged goods 12 preceding it along the weld seam.

[0063] The packaged item 12 then travels through a first longitudinal cutting and welding device 22 and a second longitudinal cutting and welding device 22', which are designed to weld the material webs 14, 16 together on opposite sides of the material webs parallel to the transport direction T, laterally of the packaged item 12, and to sever any lateral material overhang of the material webs 14, 16. The first longitudinal cutting and welding device 22 and a second longitudinal cutting and welding device 22' form a longitudinal cutting and welding system 21. Finally, the side of the packaged item facing opposite to the transport direction T is also welded and trimmed by the transverse cutting and welding device 20. The packaged item 12 is now welded and trimmed on all four sides, so that the packaged item 12 is completely enclosed by a material wrapping.

[0064] The packaging machine 10 has a first drive device 24 for driving the first feed device 18 and the second feed device 18'. The packaging machine 10 has a second drive device 26 for driving the first longitudinal cutting and sealing device 22 and the second longitudinal cutting and sealing device 22'. In particular, the packaging machine 10 can have a control device 27. The control device 27 is preferably designed to control the first drive device 24 and / or the second drive device 26.

[0065] The sequence of the transverse cutting welding device 20 and the longitudinal cutting welding devices 22, 22' is shown merely as an example in a preferred configuration. The sequence of these devices can also be different; for example, the transverse cutting welding device 20 can be arranged after the longitudinal cutting welding devices 22, 22'.

[0066] It can optionally be provided that at least one further module 28 is connected, which processes the welded material webs 14, 16. Furthermore, a labeler can be provided (not shown), which applies a label to at least one of the material webs 14, 16. Optionally, for example, a cutting station can be provided, which cuts off any excess material remaining after passing through the longitudinal cutting and welding devices 22, 22' in the longitudinal direction, closely fitting the packaged goods, and then welds it again. This can be provided in particular for packaged goods with varying widths. A material return line 30 can also be provided, which serves to receive the excess material cut off in the longitudinal cutting and welding devices 22, 22' so that it can be recycled.

[0067] The packaging machine 10 has adjustment devices 32, which serve to adjust the packaging machine 10 to a height and a width of the packaged goods 12. Possible configurations of the feed devices 18, 18', the transverse cutting and sealing device 20, and the longitudinal cutting and sealing devices 22, 22' will be explained in more detail with reference to the figures.

[0068] The Fig. 2 shows a side view of an embodiment of the longitudinal cutting and welding device 22.

[0069] The longitudinal cutting and welding device 22 has a structure corresponding to that of the longitudinal cutting and welding device 22'. The longitudinal cutting and welding devices 22 and 22' together form a longitudinal cutting and welding system 21. The longitudinal cutting and welding devices 22 and 22' are arranged opposite one another. They then weld two superimposed material webs 14, 16 on opposite sides of the material webs 14, 16, respectively, of the packaging machine 10.

[0070] The longitudinal cutting and welding device 22 is described below using the figures as an example. The longitudinal cutting and welding device 22 has a first pressure wheel 122. In principle, a different number of pressure wheels can also be provided. The first pressure wheel 122 and any further pressure wheels form a pressure assembly 125. The pressure assembly 125 interacts with a welding wheel 120. The welding wheel 120 is heated. The arrangement of the longitudinal cutting and welding device 22 is such that the material web plane 19 is tangent to or even intersects the welding wheel 120. In the embodiment shown, the first pressure wheel 122 and the second pressure wheel 124 are mounted only on ball bearings and are not themselves driven. The heated welding wheel 120 is also not driven. In principle, however, it can also be driven.

[0071] In the presentation of the Fig. 2, the welding wheel is shown in a working position. In the working position, it protrudes through the material web plane 19. In the working position, the welding wheel 120 rests against the first pressure wheel 122 and the second pressure wheel 124, or the material webs 14, 16 run between the welding wheel 120, the first pressure wheel 122, and the second pressure wheel 124. A preloading element 126 is provided that preloads the welding wheel 120 into a rest position. In the rest position, as will be explained below, the welding wheel 120 is spaced from the first pressure wheel 122 and the second pressure wheel 124. The material web plane 19 then runs freely between the welding wheel 120, the first pressure wheel 122, and the second pressure wheel 124.The welding wheel 120 is then spaced so far from the material web plane 19 that, even due to radiant heat, no heat is introduced into the material webs 14, 16 that could damage them, even if the material webs 14, 16 are stationary for a long time.

[0072] Furthermore, an adjusting device 128 is provided which moves the welding wheel 120 against the force of the pre-tensioning element 126 into the Fig. 2 shown working position.

[0073] The design of the adjusting device 128 and the pre-tensioning element 126 can be suitably selected. For example, a mechanical implementation can be selected in which the pre-tensioning element is a spring element and the adjusting device is an actuator, e.g., pneumatically operated. An electromagnetic solution can also be chosen in which the pre-tensioning element 126 is provided by permanent magnets and the adjusting device 128 by an electromagnet or a coil to which current can be applied. A combination of these elements can also be selected. In any case, the welding wheel 120 is pre-tensioned into the rest position by means of the pre-tensioning element 126. This means that, for example, in the event of a power failure, the welding wheel 120 automatically jumps into the rest position. Therefore, in the event of an emergency shutdown of the machine, no damage occurs to the material web.Furthermore, this ensures that during the transverse cutting welding process, in which the material webs 14, 16 are not conveyed in the transport direction T within the longitudinal cutting welding device, the welding wheel 120 is moved into the rest position, so that during the transverse cutting welding process, the material webs 14, 16 are also not damaged by heat input.

[0074] A first endless element 134 and a second endless element 136 are provided to drive the upper material web 14 and the lower material web 16. These are designed as belts in the illustrated embodiment. The first endless element 134 rotates over rollers 138-1, 138-2, and 138-3. The endless element 134 is driven by the roller 138-2.

[0075] A similar structure is used for the endless element 136. This element rotates over rollers 140-1, 140-2, and 140-3. The endless element 136 is driven by roller 140-2.

[0076] Downstream of the welding wheel 120 is a rotating cutting blade 130. This blade rests on a support wheel 132. The material webs 14, 16 pass through the cutting blade 130 resting on the support wheel 132 and are severed by the cutting blade 130 parallel to the transport direction T. In the illustrated embodiment, both the cutting blade 130 and the support wheel 132 are driven. Direction reversing wheels 142, 142' are provided for this purpose. In this way, the cutting blade 130 is driven via the roller 138-3, and the support wheel 132 via the roller 140-3.

[0077] The heating block 121 is arranged upstream of the welding wheel 120. Two second pressure wheels 124-1 and 124-2 are arranged on the opposite side of the material web plane 19. The material webs pass between the heating block and the two second pressure wheels 124-1 and 124-2. The heating block 121 is also heated by a heating cartridge or similar heating element.

[0078] As in the Fig. 2, the heating block extends in the transport direction T along a path that begins when the material webs are drawn through the inlet-side rollers 138-1 and 140-1 and ends shortly before the material webs enter between the welding wheel 120 and the first pressure wheel 122. The heating block 121 extends along the transport direction T, i.e. until, in the view of Fig. 2 below the welding wheel 120. In the material web plane, there is an area that lies within the projection of the welding wheel 120 onto the material web plane 19. Within this area, for example, lies the first pressure wheel 122. The heating block extends into this projection of the welding wheel 120 onto the material web plane 19. In this way, the material webs 14, 16, after running into the roller pair 138-1, 140-1, are heated almost to the point where the material webs 14, 16 come into contact with the welding wheel 120. In this way, the heating path can be significantly extended. In particular, the length of the path in the direction of transport T in the material web plane 19, along which the material webs 14, 16 are guided past the heating block 121, can be at least 120 mm, preferably at least 140 mm, more preferably at least 160 mm.

[0079] To ensure the most friction-free guidance of the material webs 14, 16, in particular the lower material web 16, over the heating block 121, a heat-conducting belt 129 is provided, which, in addition to the rollers 140-1, 140-2, 140-3, also rotates over a tensioning roller 123. The tensioning roller 123 forms a tensioning device for tensioning the heat-conducting belt 129. The heat-conducting belt 129 is made of a material with a high thermal conductivity coefficient and the lowest possible friction coefficient. For example, the material is a metal, such as copper, or a material such as polytetrafluoroethylene, e.g., Teflon®. The heat-conducting belt 129 runs over the heating block 121, so that no direct friction occurs between the lower material webs and the heating block 121. At the same time, however, heat can be introduced into the material webs 14, 16 via the heating block 121 through the heat conducting band 129.The thermally conductive tape 129 thus also runs between the pressure wheel 122 and the welding wheel 120. However, due to the thermal conductivity of the thermally conductive tape 129, the welding is not impaired here either.

[0080] Since the heat-conducting band 129 expands due to its heating, its length increases with increasing heating. To prevent the heat-conducting band from loosening, the tensioning roller 123 is provided. This is pre-tensioned outwards, e.g., by a spring. An extension of the heat-conducting band 129 would then result in the tensioning roller 123 in the Fig. 2 can be pushed straight outward, i.e., to the left, or bottom left. In this way, the circumferential length of the thermally conductive band 129 becomes longer than that of the endless element 136. The tension of the thermally conductive band can thus be maintained.

[0081] A heating device heats the welding wheel 120. Corresponding heat conducting elements are not shown and transport the heat from the heating device to the welding wheel 120 through the longitudinal cutting and welding device 22.

[0082] The Fig. 3 shows an isometric view of the longitudinal cutting and welding device in Fig. 2. The symmetrical view illustrates the position of the various belt elements. The endless element 136 for conveying the material webs is visible. An endless element 146 is also provided for conveying the material webs. Both endless elements 136 and 146 rotate over rollers 140-1, 140-2, and 140-3. Furthermore, the corresponding endless elements 134 and 144 rotate over rollers 138-1, 138-2, and 138-3.

[0083] However, the lower guide device contains the heat-conducting belt 129, which is arranged between the belt elements 136 and 146 and rotates with them. The tensioning device 123 or tensioning wheel 123 acts only on the heat-conducting belt 129.

[0084] This makes it possible to convey the material webs while simultaneously minimizing friction across the heating block at the level of the welding device. Thanks to the clamping device, heating of the thermally conductive strip 129 does not lead to a loss of tension in the thermally conductive strip 129.

[0085] The Fig. Figure 4 shows a schematic plan view of the operation of the longitudinal separation and welding device 22. Only one side of the packaged goods 12 and the upper material web 14 is shown. One long side of the material web 14 is designated 180. The material web 14 is already cross-separated with the underlying lower material web 16. The cross-separation is schematically indicated by 160. Looking again at the Fig. 2 shows the endless elements 134 and the wider endless element 144. The endless element 144 is as shown in the Fig. 3, is arranged on the side facing away from the packaged goods and primarily conveys the material webs which are not transversely welded and separated at their outer edge. The endless element 134 conveys the webs further inward on the side facing the packaged goods 12 from both the welding wheel 120 and the cutting blade 130. It can also be seen that the welding wheel 120 is arranged upstream of the cutting blade. Thus, the material webs 14, 16 are first welded by means of the welding wheel and then separated from one another by means of the cutting blade. The cutting blade can be arranged relative to the welding wheel so that the separation takes place within the width of the weld. However, it can also be provided that the weld is not severed, but the separation takes place just to the side outside the weld. After the separation at the cutting blade 130, ieDownstream in the transport direction T, the waste strip of the upper and lower material webs 14, 16, designated by reference numeral 158, is then guided away. A pair of rollers 156 can be provided that is inclined outward relative to the transport direction, i.e., a rolling direction forms an angle with the transport direction T, such that the waste strip 158 is conveyed laterally outward. In principle, however, the waste strip 158 can also simply be guided downward into a collecting container.

[0086] In the Fig. 5, the welding wheel 120 with the first pressure wheel 122 and the second pressure wheel 124 is shown cut away. Fig. 5, the welding wheel 120 is moved to the rest position. As can be seen, the material web plane 19 then runs freely between the welding wheel 120 and the first pressure wheel 122 and the second pressure wheel 124.

[0087] Due to the pressure area, a sufficiently large angular range is provided in which the material webs run along the welding wheel 120, so that a sufficiently large heat input takes into account the conveying speed and welds the material webs together.

[0088] Additionally, the heat input is increased by means of the heating block 121. This is arranged in front of the welding wheel 120 in the transport direction T, in contact with the material webs. The material webs are transported in the material web plane 19 between the two second pressure wheels 124-1, 124-2 with the heat-conducting block 121. The second pressure wheels 124-1, 124-2 press the material webs in the material web plane 19 onto the heat-conducting belt 129 on the heating block 121, so that on the section in front of the welding wheel 120, a significant heat input from the heating block 121 via the heat-conducting belt 129 into the material webs occurs. Therefore, if the angular range over which the material webs rotate around the welding wheel 120 is smaller due to the use of only a single pressure wheel 122, the heat input is sufficiently large.

[0089] The heating block 121 has a base region 160 and a contact region 162. The contact region can be widened relative to the base region 160. The area of ​​the base region 160 is shown at 164, and the width of the heating region is shown at 166. The width 166 is greater than the width 164. This results in a trapezoidal shape of the heating region 162. This makes it possible, in particular, to have the width 166 of the heating section begin immediately behind the wheel 138-1 and to be brought close to the wheel 122 without causing a collision with the wheels.

[0090] In this way, the heating block 121 can reach just before the contact point between the welding wheel 120 and the first pressure wheel 122.

[0091] The Fig. 6 shows a schematic flow diagram of a method 200 for operating a packaging machine 10.

[0092] First, a step of providing 210 a longitudinal cutting and welding device 22 is carried out, which has at least a first pair of rotating endless elements 134, 136; 144, 146 for drawing the first and second material webs 14, 16 between them and guiding the first and second material webs 14, 16 in a material web plane 19 in a transport direction T, wherein the longitudinal cutting and welding device 22 has a welding device 127, wherein the welding device 127 has a heatable welding wheel 120. Furthermore, a first pressing assembly 125 is provided for pressing the material webs 14, 16 against the welding wheel 120, wherein the first pressing assembly 125 has a first pressing wheel 122.The welding device 127 further comprises a heating block 121 which is arranged on a side opposite the welding wheel 120 with respect to the material web plane 19 and in front of the welding wheel 120 with respect to the transport direction, wherein the welding device 127 has a second pressing assembly 124 for pressing the material webs 14, 16 against the heating block 121, wherein the second pressing assembly 125 has at least one second pressing wheel 124.

[0093] When the packaging machine 10 is started, the upper material web 14 and the lower material web 16 are first conveyed 220 through the longitudinal cutting and welding device 22 by means of the at least one first pair of rotating endless elements 134, 136; 144, 146, wherein the first and the second material web 14, 16 are first conveyed along the heating block 121 and then conveyed over the welding wheel at least at one contact point, and the upper material web 14 and the lower material web 16 are first conveyed 220 through the longitudinal cutting and welding device 22 by means of the at least one first pair of rotating endless elements 134, 136; 144, 146, wherein the first and the second material web 14, 16 are first conveyed along the heating block 121 and then conveyed over the welding wheel 120 at least at one contact point.

[0094] The conveying is then stopped at intervals, i.e., a synchronized stop. The synchronized stop of the conveying of the upper material web 14 and the lower material web 16 through the longitudinal cutting and welding device 22 occurs, with the welding wheel 120 and the heating block 121 being adjusted to the rest position during the stop. This can be achieved by the adjusting device 128 no longer acting against the force of the pretensioning element 126 and a corresponding pretensioning element for the heating block. The pretensioning element 126 then causes the welding wheel 120 to be adjusted back to the rest position.

[0095] The design of the adjustment devices and the preload elements for the welding wheel 120 and the heating block 121 can be suitably selected. For example, a mechanical implementation can be selected in which the preload element is a spring element and the adjustment device is an actuator, e.g., pneumatically operated. An electromagnetic implementation can also be selected in which the preload element 126 is provided by permanent magnets and the adjustment device 128 by an electromagnet or a coil to which current can be applied. A combination of these elements can also be selected, i.e., a combination of mechanical and electromagnetic elements. In any case, the welding wheel 120 and the heating block 121 are preloaded into the rest position by means of the preload elements. This has the effect that, for example, in the event of a power failure, the welding wheel 120 and the heating block 121 automatically jump into the rest position.In the event of an emergency shutdown of the machine, no damage to the material web occurs. Furthermore, this ensures that during the cross-cutting welding process, in which the material webs 14, 16 are not conveyed in the transport direction T within the longitudinal cutting and welding device, the welding wheel 120 is moved to the rest position, so that no damage to the material webs 14, 16 due to heat input occurs during the cross-cutting welding process.

[0096] During the conveying step 220, the material webs are separated parallel to a conveying direction of the material webs by the at least one first pair of circulating endless elements 134, 136; 144, 146. The separation takes place by means of a rotating separating knife 130. The rotating separating knife 130 is driven by the same drive device as the at least one first pair of circulating endless elements 134, 136; 144, 146.

[0097] After the packaging machine 10 stops, the process 200 ends.

Claims

[1] Longitudinal cutting and welding device (22) for cutting and welding an upper material web (14) and a lower material web (16), wherein the longitudinal cutting and welding device (22) has at least a first pair of circulating endless elements (134, 136; 144, 146) for drawing the first and the second material web (14, 16) between them and guiding the first and the second material web (14, 16) in a material web plane (19) in a transport direction (T), wherein the longitudinal cutting and welding device (22) has a welding device (127), wherein the welding device (127) has a heatable welding wheel (120) and a first pressing assembly (125) for pressing the material webs (14, 16) against the welding wheel (120), wherein the first pressing assembly (125) has a first pressing wheel (122, 124), wherein the Welding device (127) has a heating block,which is arranged on a side opposite the welding wheel (120) with respect to the material web plane (19) and in front of the welding wheel (120) with respect to the transport direction, wherein the welding device (127) has a second pressing assembly for pressing the material webs (14, 16) against the heating block, wherein the second pressing assembly (125) has at least one second pressing wheel. [2] Longitudinal cutting welding device according to claim 1, wherein the first pressure assembly has exactly one first pressure wheel. [3] Longitudinal cutting and welding device according to claim 1 or 2, wherein the second pressure assembly has exactly two second pressure wheels. [4] Longitudinal cutting welding device according to one of claims 1 to 3, wherein the welding wheel (120) is adjustable between a working position in which the first pressing assembly (125) bears against the welding wheel (120) and a rest position in which the welding wheel (120) is spaced from the first pressing assembly (125), and wherein the welding device (127) has at least one first prestressing element (126) which prestresses the welding wheel (120) into the rest position. [5] Longitudinal cutting and welding device according to one of claims 1 to 4, wherein the heating block is adjustable between a working position in which the second pressing assembly (125) rests against the heating block and a rest position in which the heating block is spaced from the pressing assembly (125), and wherein the welding device (127) has at least one second biasing element (126) which biases the heating block into the rest position. [6] Longitudinal cutting welding device according to one of claims 1 to 5, wherein the welding device (127) further comprises a circumferential heat conducting band which is arranged such that it circulates around at least the heating block between the heating block and the lower material web (16). [7] Longitudinal cutting welding device according to claim 6, wherein the heat conducting band is made of a metal or of polytetrafluoroethylene. [8] Longitudinal cutting welding device according to claim 6 or 7, wherein the longitudinal cutting welding device further comprises a drive device for driving the heat conducting band. [9] Longitudinal cutting and welding device according to one of claims 6 to 8, wherein the longitudinal cutting and welding device further comprises a tensioning device for tensioning the heat-conducting band, in particular for compensating for temperature-induced expansion of the heat-conducting band. [10] Longitudinal cutting and welding device (22) according to one of claims 1 to 9, wherein the superimposed material webs (14, 16), in particular in the working position, bear against the welding wheel (120) in at least one contact point, in particular in a contact area (162). [11] Longitudinal cutting welding device (22) according to one of claims 1 to 10, wherein the welding wheel (120) and the first pressure wheel (122) of the first pressure assembly (125) are jointly driven or are arranged to be free-running. [12] Longitudinal cutting welding device (22) according to one of claims 1 to 11, wherein the at least one second pressure wheel (124-1, 124-2) of the second pressure assembly (125) is driven. [13] Longitudinal cutting welding device (22) according to one of claims 1 to 12, wherein an outer circumference of the welding wheel (120) extends through the material web plane. [14] Longitudinal cutting and welding device (22) according to one of claims 1 to 13, wherein the longitudinal cutting and welding device (22) further comprises a longitudinal cutting device (130, 132) for cutting the superimposed material webs (14, 16) parallel to the transport direction (T), wherein the longitudinal cutting device comprises a rotating circular blade (130) and a support wheel (132) for supporting the material webs (14, 16) against the circular blade (130). [15] Longitudinal cutting welding device (22) (10) according to claim 14, wherein the circular blade (130) and the support wheel (132) are driven jointly. [16] Longitudinal cutting and welding device (22) according to claim 14 or 15, wherein the longitudinal cutting and welding device (22) further comprises at least one second pair of circulating endless elements (144, 146) which pull the superimposed material webs (14, 16) between them on the two opposite longitudinal sides of the material webs (180) and guide them in the material web plane (19), wherein the circular knife is arranged in the material web plane (19) orthogonal to the transport direction (T) between the first pair of endless elements of the respective longitudinal cutting and welding device (22, 22') and the second pair of endless elements of the same longitudinal cutting and welding device (22, 22'). [17] Longitudinal cutting and welding device (22) according to claim 16, wherein the second pair of endless elements of the longitudinal cutting and welding devices (22, 22') each rotate in a second plane of rotation, the second plane of rotation running parallel to the circular blade plane. [18] Longitudinal cutting and welding device (22) according to claim 17, wherein the first and the second longitudinal cutting and welding device (22, 22') each have a pair of rollers (156) arranged downstream of the first and / or second pairs of endless elements in the transport direction (T), wherein the respective pair of rollers of the longitudinal cutting and welding devices (22, 22') is designed to pull the two material webs between them and to guide them in the material web plane (19), wherein the rollers of the respective pair of rollers run outwards relative to the transport direction (T) at a pre-tensioning roller angle, in particular in such a way that a material overhang (158) laterally severed by means of the longitudinal cutting device is transported away by the pair of rollers of the respective longitudinal cutting and welding device (22, 22'). [19] Longitudinal cutting and welding device (22) according to one of claims 14 to 18, wherein the longitudinal cutting device (130) is arranged behind the welding device (128) in the transport direction (T). [20] Longitudinal cutting and welding system (21) with a first and a second longitudinal cutting and welding device (22, 22') for welding the material webs (14, 16) parallel to the transport direction (T) on two opposite longitudinal sides (180) of the material webs (14, 16), wherein both the first longitudinal cutting and welding device (22) and the second longitudinal cutting and welding device (22') are longitudinal cutting and welding devices according to one of claims 1 to 19, wherein the first and the second longitudinal cutting and welding device (22, 22') each have at least the first pair of circumferential endless elements (134, 136; 144, 146) which pull the first and the second material web (14, 16) between them on the two opposite longitudinal sides (180) of the material webs (14, 16) and guide them in a material web plane (19). [21] Packaging machine (10) for packaging a packaged item (12) with an outer packaging produced from an upper material web (14) and a lower material web (16), wherein the packaging machine (10) has a longitudinal separation and welding system according to claim 20. [22] Method (200) for longitudinally separating and welding an upper and a lower material web (14, 16), comprising the following steps: • Providing (210) a longitudinal separation welding device (22) having at least a first pair of circulating endless elements (134, 136; 144, 146) for drawing the first and the second material web (14, 16) between them and guiding the first and the second material web (14, 16) in a material web plane (19) in a transport direction (T), wherein the longitudinal separation welding device (22) has a welding device (127), wherein the welding device (127) has a heatable welding wheel (120) and a first pressing assembly (125) for pressing the material webs (14, 16) against the welding wheel (120), wherein the first pressing assembly (125) has a first pressing wheel (122, 124), wherein the welding device (127) has a heating block which is arranged on a surface which is parallel to the welding wheel (120) with respect to the material web plane (19) opposite side and in front of the welding wheel (120) with respect to the transport direction,wherein the welding device (127) has a second pressing assembly for pressing the material webs (14, 16), wherein the second pressing assembly (125) has at least one second pressing wheel; and, • Conveying (220) the upper material web (14) and the lower material web (16) through the longitudinal cutting and welding device (22) by means of the at least one first pair of circulating endless elements (134, 136; 144, 146), wherein the first and the second material web (14, 16) are first conveyed along the heating block and then conveyed over the welding wheel at least at one contact point. [23] The method of claim 22, further comprising the step of: • Stopping or cyclical stopping (230) of the conveying of the upper material web (14) and the lower material web (16) through the longitudinal cutting welding device (22), wherein the welding wheel (120) and the heating block are adjusted away from the upper and lower material webs (14, 16) during the stopping.

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