Device and method for crimping a flat web and machine for producing paper filters

Abstract

The invention relates to a device (12) and a method for crimping a flat web (6) of a material used in the tobacco processing industry and also relates to a machine (2) for producing paper filters (24). A crimping station (26) with a first crimping roller (32a) and with a second crimping roller (34b) is configured to produce a plurality of longitudinal lines in the flat web (6), along which the flat web (6) can be easily folded. A detection unit (28) is configured and designed to detect a splice and / or a spatially limited enlargement of a material thickness of the flat web (6) in the longitudinal direction L of the flat web (6) and to generate an opening signal S. Adjustment means (36) adjust at least one of the two crimping rollers (32a, 32b) along an adjustment path (38) between a working position and a disengagement position. A control unit (30) controls the adjusting means (36) in response to the opening signal S, such that in an opening movement the at least one crimping roller (32a, 32b) travels in the direction of the disengagement position and in a closing movement travels in the direction of the working position, in two mutually different sections of the adjustment path (38) at mutually different travelling speeds.

Description

[0001] Device and method for crimping a flat strip and machine for producing paper filters

[0002] Description

[0003] The invention relates to a device for crimping a flat web made of a material from the tobacco processing industry, comprising a crimping station with a first crimping roller mounted so as to be rotatable about a first axis of rotation and with a second crimping roller mounted so as to be rotatable about a second axis of rotation, which are operatively coupled and designed to produce a plurality of longitudinal lines in the flat web as it passes between the crimping rollers, along which lines the flat web is easily foldable, in particular in its transverse direction.Furthermore, the invention relates to a method for crimping a flat sheet made of a material from the tobacco processing industry, comprising the following steps: providing a flat sheet and feeding the flat sheet to a crimping station; creating a plurality of longitudinal lines in the flat sheet along which the flat sheet is easily foldable, particularly in its transverse direction, by passing the flat sheet in the crimping station between a first crimping roller rotating about a first rotational axis and a second crimping roller rotating about a second rotational axis. Finally, the invention relates to a machine for producing paper filters.

[0004] In the tobacco processing industry, flat sheets are processed and used for various purposes. For example, flat sheets made from a paper material from the tobacco processing industry are processed into paper filters. A frequently performed process step in the processing of flat sheets is the so-called "crimping" of the flat sheet. This term describes a process in which a large number of longitudinal lines are introduced into the flat sheet. The longitudinal lines are often equidistant in the transverse direction of the flat sheet and extend in the longitudinal direction of the flat sheet. Furthermore, they are often continuous longitudinal lines that extend uninterrupted along the longitudinal direction of the flat sheet.

[0005] The longitudinal lines introduced into the flat sheet during crimping ensure that the flat sheet can be easily gathered or folded in its transverse direction, i.e., perpendicular to the longitudinal lines. Gathering the flat sheet is further facilitated by the fact that during crimping, not only are longitudinal lines introduced into the flat sheet, but the cross-section of the flat sheet, viewed in a plane perpendicular to its longitudinal direction, is also altered so that it acquires at least an approximately zigzag structure.

[0006] The longitudinal lines are introduced into the flat web using known crimping rollers. Crimping rollers are often made up of a large number of disks arranged on a common axis. The disks are aligned parallel to one another and perpendicular to the common axis. In the area of ​​the outer surfaces, the disks of the crimping rollers are separated from one another by circumferential grooves. The two crimping rollers engage with one another in such a way that a disk of one crimping roller extends into the groove between the disks of the other crimping roller that interacts with it. By adjusting the distance between the crimping rollers, the engagement depth of the disks and grooves, which is also referred to as the crimping depth, can be adjusted. A machine in the tobacco processing industry that includes a crimping device is known, for example, from DE 10 2017 007 455 A1.

[0007] The flat sheet is crimped by passing it between the crimping rollers. Longitudinal lines are introduced into the flat sheet, and its cross-section is altered as described. Based on this structure, the flat sheet can then be gathered and further processed, for example, in a strand-forming unit into a paper filter strand. Paper filters are used in traditional rod-shaped products in the tobacco processing industry, but also in so-called tobacco heated products, also known as heat-not-burn products. When tobacco heated products are consumed, the tobacco material is heated and not burned.

[0008] Flat webs in the tobacco processing industry have very different material thicknesses. To achieve the desired crimping effect, it is therefore desirable to change or adjust the distance between the crimping rollers depending on the thickness of the processed material. WO 2019 / 123210 A1 discloses a method in which the material thickness of the flat web is measured with a sensor. The distance between the crimping rollers is adjusted as a function of this distance in order to achieve the desired result in the crimping process.

[0009] It is an object of the invention to provide a device for crimping a flat sheet made of a material from the tobacco processing industry, a method for crimping a flat sheet made of a material from the tobacco processing industry and a machine for producing paper filters, wherein the most continuous processing of the flat sheet is to be possible.

[0010] The object is achieved by a device for crimping a flat web made of a material from the tobacco processing industry, comprising: a crimping station with a first crimping roller mounted so as to be rotatable about a first rotational axis and with a second crimping roller mounted so as to be rotatable about a second rotational axis, which are operatively coupled and configured to produce a plurality of longitudinal lines in the flat web as it passes between the crimping rollers, along which lines the flat web is easily foldable, in particular in its transverse direction, wherein this device is further developed by: a detection unit configured and designed to detect a splice point and / or an increase in the material thickness of the flat web, which is spatially limited in the longitudinal direction of the flat web and which exceeds a predeterminable limit value, and to generate an opening signal in response thereto,wherein the detection unit is arranged upstream of the crimping station in the material flow direction,

[0011] Adjustment means which are set up and designed to move at least one of the two crimping rollers relative to one another along an adjustment path between a working position, in which longitudinal lines are generated in the flat web when the flat web passes between the crimping rollers, and a disengagement position, wherein a distance between the first and the second rotational axes is smaller in the working position than in the disengagement position, a control unit coupled to the detection unit and the adjustment means, which is set up and designed such that the adjustment means, in response to the opening signal, move the at least one crimping roller in an opening movement towards the disengagement position, move the at least one crimping roller in a closing movement towards the working position, and carry out the closing movement in two mutually different sections of the adjustment path at mutually different travel speeds.

[0012] The device advantageously makes it possible to process flat webs continuously, even if they have splices or increases in material thickness. Splices occur when an outgoing flat web is joined to a flat web to be processed subsequently. The flat webs, which may be provided on reels, for example, are joined to form an endless flat web using a splicing device to enable a continuous process. Increases in the material thickness of the flat web sometimes occur within the material of the flat web, i.e. during the processing of the flat web, which may be provided on a reel, for example. Such increases in material thickness arise, for example, from splicing processes carried out during the production of the flat web.Both a splice and an increase in material thickness result in a flat web with a greater material thickness briefly passing through the crimping rollers. Without the measures taken in the device according to aspects of the invention, namely the moving apart or disengaging of the crimping rollers in response to the opening signal, undesirable discontinuities in the production process occur. For example, when a splice passes through the crimping rollers, a mechanical shock can occur that stresses the crimping rollers and their mechanical mounts, for example their bearings. Such an event occurring during the production process leads to uncertainty among operating personnel and can cause damage to the crimping device. To avoid this, it is provided that in response to the opening signal, at least one crimping roller is moved in an opening movement towards the disengagement position.After the splice has been passed through or the material thickness has been increased by the pair of crimping rollers, the crimping rollers are moved back toward their working position to continue the production process. During the brief period in which the crimping rollers are in the disengaged position, the flat web is not crimped in the usual manner. This means that articles or intermediate products manufactured from this area of ​​the flat web by the tobacco processing industry must be removed from the ongoing production process. They are rejected because they generally do not meet the desired quality requirements.

[0013] In order to keep the resulting waste as low as possible, it is desirable to carry out the closing movement as quickly as possible after the splice has been completed or the material thickness of the flat web has been increased. The aim is to return the crimping rollers to their working position as quickly as possible so that the production process can continue with the desired quality. In this context, however, it must be noted that the working position must be set very precisely. The working position is set with accuracies in the range of a few micrometers (pm) to approximately 10 pm. In other words, a very precise positioning of the crimping rollers is carried out. In many cases, exact positioning is only possible with correspondingly low travel speeds of the crimping rollers.In order to achieve the goal of keeping the resulting waste as low as possible on the one hand and to enable exact positioning of the crimping rollers relative to each other on the other, the closing movement is carried out at two different travel speeds.

[0014] The control unit is preferably configured and designed to move the adjustment means, with which the distance between the crimping rollers is adjusted, in response to the opening signal in a rapid opening movement, i.e., at a high travel speed, toward the disengagement position. The opposite closing movement occurs after a predetermined or predeterminable time period, i.e., at a slightly later point in time. The time period that elapses between the opening movement and the closing movement serves to allow the crimping roller pair to pass through the splice point or increase the material thickness. The value of this time period can be determined, for example, based on empirical tests.The control unit is further preferably configured and designed to control the adjustment means such that, after the aforementioned time period has elapsed, the crimping rollers are again moved toward the working position at high speed. However, the crimping rollers are not moved at high speed along their entire travel path, but rather only over a predominant portion, for example. The remaining portion of the travel path is traversed at a significantly lower speed to enable the working position to be approached with high precision.

[0015] The travel path of the crimping rollers, which results in particular from the difference in the axial distance between the first rotational axis and the second rotational axis when the crimping rollers are in the working position on the one hand and in the disengagement position on the other, can be adjusted depending on the material thickness of the processed flat strip. For example, the material thickness of the processed flat strips is between 35 μm and 500 μm.

[0016] Depending on this material thickness, a crimping depth is first set, i.e. the depth at which the crimping rollers engage with each other. This crimping depth determines the working position. If a splice or an area of ​​greater material thickness is detected in the flat web, the material thickness in this area is easily twice as thick as in the areas before and after it. Accordingly, the crimping depth is increased during the disengagement process, i.e. during the opening movement towards the disengagement position, for example by the value of the increase in material thickness in the area of ​​the splice. As already explained, this increase in material thickness is approximately the material thickness of the flat web being processed (assuming that the material thickness of the flat web doubles in the area of ​​the splice).Thus, the travel distance determining the release width, i.e., the distance between the working position and the opening position, can also be, for example, in the range between 35 pm and 500 pm. According to further embodiments, the travel distance is provided between 50 pm and 300 pm, and in particular between 100 pm and 200 pm.

[0017] According to an advantageous embodiment, the device is further developed in that the closing movement takes place starting from the disengagement position up to the working position, wherein the control unit is set up and designed to control the adjustment means in such a way that the closing movement is carried out at a second, in particular temporally constant, travel speed in a first partial section, which is first traveled through starting from the disengagement position and takes up a predominant part of the adjustment path traveled during the closing movement, and the closing movement is carried out at a third, in particular temporally constant, travel speed in a second partial section, which is traveled through subsequent to the first partial section, wherein the third travel speed is lower than the second travel speed.

[0018] The closing movement, which occurs at a higher travel speed in the first section than in the second section, advantageously minimizes the area of ​​the flat web where insufficient crimping occurs due to the disengaged crimping rollers. Starting from the opening position, the crimping rollers are moved toward the working position at high travel speed. To ensure precise control of the working position, the further closing movement in the second section of the adjustment path occurs at a lower speed.

[0019] According to an advantageous development of the device, it is further provided that the opening movement takes place starting from the working position up to the disengagement position and the control unit is set up and designed to control the adjustment means such that the opening movement is carried out at a first, in particular temporally constant, travel speed in a partial section which occupies the at least predominant part of an adjustment path traversed during the opening movement, wherein the (previously mentioned) third travel speed is lower than the first travel speed and the third travel speed is lower than the second travel speed. It is further provided in particular that the first travel speed is greater than or equal to the second travel speed.

[0020] In other words, in response to the opening signal, the crimping rollers are initially moved quickly towards the opening position, namely at the first travel speed. After passing through the splice point or increasing the material thickness of the flat web, the crimping rollers are again moved towards the working position at a comparatively high travel speed, the second travel speed, which is, however, less than or equal to the opening speed. In order to be able to control the working position precisely, the crimping rollers are then moved at a lower speed, the third travel speed. This procedure has proven advantageous. It can minimize the resulting waste, and at the same time damage to the crimping device, for example from a splice point, can be prevented. The desired working position is reached with great precision.

[0021] According to a further advantageous embodiment, the first subsection occupies at least 80%, in particular at least 85%, and in particular at least 90%, of the adjustment path traversed during the closing movement. The specified values ​​for the first subsection of the adjustment path traversed during the closing movement have proven advantageous in practical tests.

[0022] According to an alternative embodiment, the device is further developed in that the control unit is designed and configured to change an adjustment point at which the transition between the first and the second sub-section takes place, wherein the control unit is in particular designed and configured to change the adjustment point depending on a parameter received as part of a user input. The user input can, similar to the previously mentioned fixed values, again be given as a percentage. The user input can be selected such that the quality requirements desired by the user for the crimping process, for example a crimp depth desired by the user, are already achieved during the transition from the first to the second sub-section.In other words, products produced from the flat web during the crimping roller process in the second section already meet the quality requirements specified by the user. This measure can further reduce the resulting waste.

[0023] According to a further advantageous embodiment, the device is further developed in that the adjustment means comprise a linear guide and at least one displacement motor, wherein the displacement motor is set up and designed to move the at least one crimping roller, guided by the linear guide, along the adjustment path, wherein the adjustment means further comprise a rotary encoder coupled to the displacement motor and a linear encoder coupled to the linear guide, with each of which an adjustment of the at least one crimping roller along the adjustment path can be measured, wherein the control unit is further set up and designed to feedback-regulate the opening movement taking into account the measured values ​​recorded by the rotary encoder and to feedback-regulate the closing movement taking into account the measured values ​​recorded by the rotary encoder and the linear encoder.

[0024] A linear encoder allows for more precise measurement of the position of the crimping rollers than a rotary encoder. The positioning of the crimping rollers relative to each other can therefore be performed more precisely based on the measured values ​​of the linear encoder than is possible based on the measured values ​​obtained from a rotary encoder coupled to the traversing motor. This is primarily due to the fact that the mechanical error chain, which in a rotary encoder particularly includes an adjustment gear, can be shortened. For this reason, controlling the spacing of the crimping rollers in the second subsection using the measured values ​​acquired by a linear encoder has proven advantageous.

[0025] This embodiment can be advantageously developed in that the control unit is set up and designed to control the closing movement in the first subsection taking into account the measured values ​​detected by the rotary encoder and in the second subsection taking into account the measured values ​​detected by the linear encoder.

[0026] According to a further advantageous embodiment, the device for crimping the flat strip is further developed in that the detection unit comprises at least one sensor which is designed and configured to measure the material thickness of the flat strip, wherein the sensor is in particular an optical sensor, furthermore in particular the sensor is designed and configured to measure a translucency of the flat strip.

[0027] An opening signal can be generated by the sensor, especially if the measured value of the material thickness of the flat sheet lies outside a reference range or tolerance range or exceeds a specified limit. The optical sensor is, for example, a laser sensor. The sensor can also be designed as a mechanical switch, microwave sensor, high-frequency sensor, and / or ultrasonic sensor.

[0028] In the device according to aspects of the invention, at least one of the two crimping rollers is mounted so that it can move relative to the other crimping roller. This allows the mutual distance between the crimping rollers to be varied. The adjustment means therefore only act on one of the two crimping rollers, with the other crimping roller that interacts with it being fixedly mounted. According to further embodiments, it is provided that both crimping rollers are movable and are thus moved relative to one another. The first and second crimping rollers are arranged in the crimping station in particular such that the first axis of rotation, about which the first crimping roller is rotatably mounted, and the second axis of rotation, about which the second crimping roller is rotatably mounted, are aligned at least approximately parallel to one another. Furthermore, the crimping rollers are designed in particular such that the longitudinal lines introduced into the flat web are linear embossings.The lines are, in particular, continuous, meaning uninterrupted. This consideration naturally excludes the areas where the splice or the increase in the material thickness of the flat web is located. In addition to continuous lines, intermittent lines can also be provided, as long as the lines result in sufficient embossing or weakening of the flat web so that it is gathered in the transverse direction, can be gathered, or is easily foldable.

[0029] The object is further achieved by a method for crimping a flat strip made of a material from the tobacco processing industry, comprising the following steps:

[0030] Providing a flat track and feeding the flat track to a crimping station,

[0031] Creating a plurality of longitudinal lines in the flat web, along which the flat web is easily foldable, particularly in its transverse direction, by guiding the flat web in the crimping station between a first crimping roller rotating about a first axis of rotation and a second crimping roller rotating about a second axis of rotation, wherein this method is further developed by the following steps: detecting a splice point and / or a spatially limited increase in the material thickness of the flat web in the longitudinal direction of the flat web that exceeds a predeterminable limit value, in response thereto, generating an opening signal with a detection unit arranged upstream of the crimping station in the material flow direction, in response to the opening signal, moving the at least one crimping roller in an opening movement towards a disengagement position, moving the at least one crimping roller in a closing movement towards the working position,wherein the closing movement is carried out in two mutually different sections of an adjustment path with mutually different travel speeds, wherein the movement of the crimping rollers is carried out by adjusting means which are designed and constructed to move at least one of the two crimping rollers relative to one another along an adjustment path between the working position, in which longitudinal lines are generated in the flat web when the flat web passes between the crimping rollers, and the disengagement position, wherein a distance between the first and the second rotational axes is smaller in the working position than in the disengagement position.

[0032] The method for crimping a flat strip made of a material used in the tobacco processing industry offers the same or similar advantages as those already mentioned with regard to the device for crimping the flat strip. The same applies to the advantageous and optional further development options mentioned in connection with the device.

[0033] According to one embodiment, the method is further developed in that the closing movement takes place between the disengagement position and the working position, wherein the closing movement is carried out at a second, in particular temporally constant, travel speed in a first partial section, which is first traversed starting from the disengagement position and takes up a predominant part of the adjustment path traversed during the closing movement, and the closing movement is carried out at a third, in particular temporally constant, travel speed in a second partial section, which is traversed subsequently to the first partial section, wherein the third travel speed is lower than the second travel speed.

[0034] According to a further advantageous embodiment, it is further provided that the opening movement takes place between the working position and the disengagement position, wherein the opening movement is carried out in a partial section which occupies the at least predominant part of an adjustment path traversed during the opening movement, at a first, in particular temporally constant, travel speed, wherein the third travel speed is lower than the first travel speed and the third travel speed is lower than the second travel speed.

[0035] In particular, it is provided that the first travel speed is greater than or equal to the second travel speed. Furthermore, it is provided that the first or second travel speed is the highest of all travel speeds, the second travel speed is less than or equal to the first travel speed, and the third travel speed is the lowest travel speed.

[0036] According to a further advantageous embodiment, the method is further developed in that the second subsection occupies at least 80%, in particular at least 85%, further in particular at least 90% of the adjustment path traversed during the closing movement.

[0037] According to an alternative embodiment, it is further provided that an adjustment point is changed at which the transition between the first and the second subsection takes place, wherein the adjustment point is changed in particular as a function of a parameter received as part of a user input.

[0038] According to a further advantageous embodiment, it is further provided that the adjustment means comprise a linear guide and at least one displacement motor, wherein the displacement motor moves the at least one crimping roller, guided by the linear guide, along the adjustment path, wherein the adjustment means further comprise a rotary encoder coupled to the displacement motor and a linear encoder coupled to the linear guide, with each of which an adjustment of the at least one crimping roller along the adjustment path is measured, wherein the opening movement is controlled with feedback taking into account the measured values ​​recorded by the rotary encoder and the closing movement is controlled with feedback taking into account the measured values ​​recorded by the rotary encoder and the linear encoder.

[0039] It is also advantageous if the measured values ​​recorded by the rotary encoder and the measured values ​​recorded by the linear encoder are used as follows, namely in such a way that the closing movement is controlled with feedback in the first subsection taking into account the measured values ​​recorded by the rotary encoder and in the second subsection taking into account the measured values ​​recorded by the linear encoder.

[0040] According to a further advantageous embodiment, the method is further developed in that the detection unit comprises at least one sensor, wherein the material thickness of the flat web is measured with the sensor, and wherein the sensor is in particular an optical sensor, which further measures in particular a translucency of the flat web.

[0041] Again, the opening signal can be generated when the measured material thickness value lies outside a reference or tolerance range. The measurement can be performed optically, for example, using a laser. For example, the translucency of the flat sheet material is measured, and this value can be used to determine the material thickness of the flat sheet. Other options for determining the material thickness include a measurement with a mechanical probe, a microwave measurement, a high-frequency measurement, or even an ultrasonic measurement.

[0042] The object is further achieved by a machine for producing paper filters, comprising a supply unit for providing a flat web made of a paper material from the tobacco processing industry and a device for crimping the flat web according to one or more of the aforementioned embodiments. The machine further comprises a feed unit which is designed and configured to feed the flat web to the crimping device, a gathering unit which is designed and configured to gather the crimped flat web transversely to its longitudinal direction, a format unit which is designed and configured to produce a paper filter strand from the gathered, crimped flat web, and a cutting unit which is designed and configured to cut paper filters to length from the paper filter strand.

[0043] Advantageously, the machine according to aspects of the invention makes it possible to produce paper filters of the highest quality with minimal waste. The machine allows for a continuous production process that does not need to be interrupted at splice points in the flat web. With conventional machines, it is necessary to briefly interrupt the production process at a splice point in the flat web or to continue it at a reduced speed and manually pass through the splice point. The products manufactured from this area of ​​the flat web must be discharged. Such a labor-intensive and lengthy interruption of the production process is advantageously not necessary with the machine according to the aforementioned aspects of the invention.

[0044] According to one embodiment, the machine is further developed by a discharge unit which is designed and configured to discharge paper filters produced from the paper filter strand from the ongoing process, wherein the control unit of the crimping device is further configured to trigger a discharge process of the discharge unit in response to the opening signal of the detection unit.

[0045] According to a further advantageous embodiment, it is provided that the control unit is further designed and configured to synchronize the opening movement with the opening signal in such a way that the splice point and / or the increase in the material thickness of the flat web passes through the crimping rollers before the opening movement is completed.

[0046] The synchronization of the opening movement to the opening signal, such that the splice point or the increase in the material thickness of the flat web passes through the crimping roller pair before the opening movement is completely completed, allows the time period between the opening movement and the closing movement to be minimized.

[0047] This length of time is chosen as a safety margin, so that it can be assumed with near certainty that the splice point or the increase in the material thickness of the flat web has already passed the crimping roller pair at the beginning of the closing movement. This prevents damage to the crimping roller pair due to this thickening of the flat web. At the same time, the area that cannot be processed into products of the desired quality can be minimized.

[0048] Further features of the invention will become apparent from the description of embodiments of the invention together with the claims and the accompanying drawings. Embodiments of the invention may incorporate individual features or a combination of several features.

[0049] Within the scope of the invention, features marked with “in particular” or “preferably” are to be understood as optional features.

[0050] The invention is described below, without limiting the general inventive concept, using exemplary embodiments with reference to the drawings, whereby express reference is made to the drawings for all details of the invention not explained in more detail in the text. They show:

[0051] Fig. 1 is a schematically simplified representation of a machine for producing paper filters, comprising a device for crimping a flat web,

[0052] Fig. 2 is a schematic representation of a curve of the crimping depth of the crimping rollers as a function of time, during an opening movement and a closing movement, and

[0053] Fig. 3 and 4 simplified perspective views of a crimping station for crimping a flat strip.

[0054] In the drawings, identical or similar elements and / or parts are provided with the same reference numbers, so that a repeated presentation is omitted.

[0055] Fig. 1 shows a simplified schematic representation of a machine 2 for producing paper filters 24. The machine 2 comprises a supply unit 4 for supplying a flat web 6, which consists, for example, of a paper material from the tobacco processing industry. The flat web 6 is supplied on a reel 8. To enable a continuous production process, the supply unit 4 comprises a reel changer or is designed as such. When the flat web 6 runs out of the reel 8, a seamless change to another reel 8' takes place. The flat web 6' unwound from this reel 8' is shown in Fig. 1 with a dashed line. To seamlessly join the two flat webs 6, 6' together, the machine 2 comprises a splicing unit 10.

[0056] The flat web 6 is fed from the splicing unit 10, optionally using an intermediate storage device not shown in Fig. 1, in the transport direction T to a device 12 for crimping the flat web 6, which will also be referred to below as the crimping device 12. The flat web is transported in its longitudinal direction L, which corresponds to the transport direction T. A feed unit 14 is provided, which is designed and configured to feed the flat web 6 to the crimping device 12. The feed unit 14 is schematically illustrated in Fig. 1 by a pair of transport rollers. Downstream of the crimping device 12, the crimped flat web enters a gathering unit 16. The gathering unit 16 is designed and configured to gather the crimped flat web transversely to its longitudinal direction.For example, the shirring unit 16 is a flat guide that tapers conically in the transport direction T, thus gathering the flat web. Further downstream is a formatting unit 18, in which a paper filter strand 20 is produced from the crimped flat web. Using a cutting unit 22, individual paper filters 24 are cut to length from the paper filter strand 20. Further downstream, the machine 2 also includes a discharge unit 52, with which individual paper filters can be discharged from the production process.

[0057] The crimping device 12 comprises a crimping station 26, a detection unit 28 and a control unit 30. The control unit 30 is data-technically coupled to the crimping station 26 and the detection unit 28, for example via data lines shown in the figure and not designated in more detail.

[0058] The crimping station 26 comprises a first crimping roller 32a, which is mounted for rotation about a first rotation axis 34a. Furthermore, the crimping station 26 comprises a second crimping roller 32b, which is mounted for rotation about a second rotation axis 34b. The first and second crimping rollers 32a, 32b are operatively coupled. For example, the rotation speeds of the two crimping rollers 32a, 32b are coordinated with one another. For this purpose, drives (not shown in the figure), for example, drive motors, of the crimping rollers 32a, 32b are controlled accordingly. This control can be implemented, for example, via the control unit 30.

[0059] The two crimping rollers 32a, 32b are further configured to impart a plurality of longitudinal lines into the flat web 6 as it passes between the crimping rollers 32a, 32b. These longitudinal lines are, for example, embossed lines. Along these longitudinal lines, the flat web 6 is easily foldable, particularly in its transverse direction, which is oriented transversely to the longitudinal direction L of the flat web 6, so that it can be gathered in the gathering unit 16 arranged downstream.

[0060] The crimping rollers 32a, 32b are designed in a manner known per se.

[0061] They comprise, for example, a plurality of discs arranged parallel to one another, which are spaced apart from one another by circumferential grooves in the area of ​​a circumferential surface of the respective crimping roller 32a, 32b. The discs of one crimping roller 32a, 32b engage in the grooves of the other crimping roller 32a, 32b, so that the aforementioned lines are embossed on the flat strip 6 as it passes between the crimping rollers 32a, 32b. Furthermore, the flat strip 6 is embossed or pre-folded in a zigzag shape in cross-section, viewed in a plane perpendicular to its longitudinal direction L.

[0062] The detection unit 28 is arranged upstream of the crimping station 26 in the material flow direction T, i.e. arranged upstream in the material flow direction T. The detection unit 28 is set up and designed to detect a splice point and / or an increase in the material thickness of the flat web 6 that is spatially limited in the longitudinal direction L of the flat web 6. In the following, reference is made to a splice point as an example. Such a splice point is created when the outgoing flat web 6 is connected to the further flat web 6' with the aid of the splicing unit 10. The corresponding statements also apply to an increase in the material thickness of the flat web 6 that is spatially limited in the longitudinal direction L of the flat web 6, which is caused, for example, by a splice carried out during the production process of the flat web 6.

[0063] The detection unit 6 is set up and designed to measure the material thickness of the flat web 6 and to determine whether a predetermined or predeterminable limit value is exceeded. In response, the detection unit 28 generates an opening signal S. This opening signal S is communicated from the detection unit 28 to the control unit 30. In response to the opening signal S, the control unit 30 controls adjustment means 36 of the crimping station 26. The adjustment means 36, for example a correspondingly designed and configured adjustment motor, are set up and designed to move at least one of the two crimping rollers 32a, 32b along an adjustment path 38. In the embodiment shown in Fig. 1, the first crimping roller 32a is adjustable by way of example. The adjustment path 38 illustrates this adjustability of the first crimping roller 32a.For example, the first rotational axis 34a of the first crimping roller 32a is shifted linearly, so that the distance between the first and second rotational axes 34a, 34b changes. For clarity, the adjustment path 38 is shown exaggerated.

[0064] The adjustment means 36 are configured to move the first crimping roller 32a between a working position and a disengagement position. In the working position, longitudinal lines are imprinted between the crimping rollers 32a, 32b of the flat web 6 as the flat web 6 passes. In the disengagement position, the distance between the two rotational axes 34a, 34b of the crimping rollers 32a, 32b is greater than in the working position. In the disengagement position, the crimping rollers 32a, 32b are also moved far enough apart that a splice present in the flat web 6 can pass the crimping rollers 32a, 32b without a mechanical event, such as a mechanical impact, occurring in the crimping station 26.

[0065] The control unit 30 is configured and designed to control the adjustment means 36 of the crimping station 26 such that the first crimping roller 32a is moved in an opening movement toward the disengaged position in response to the opening signal S. After a predetermined or predeterminable period of time, the first crimping roller 32a is moved back toward the working position in a closing movement. The closing movement occurs in two different sections of the adjustment path 38 at different travel speeds.

[0066] The detection unit 28 used to detect the material thickness of the flat web 6 is, for example, a sensor configured to measure the translucency of the flat web 6. In other words, an optical sensor is used. For example, it is a laser sensor.

[0067] The machine for producing paper filters 24 shown in Fig. 1 includes the discharge unit 52, illustrated by an arrow. The discharge unit 52 is designed and configured to discharge paper filters 24 produced from the paper filter strand 20 from the ongoing process. The control unit 30 of the crimping device 12 is configured to trigger a discharge process of the discharge unit 52 in response to the opening signal S of the detection unit 28. The exact timing of the discharge process takes into account the production speed.

[0068] The opening movement and closing movement of the first crimping roller 32a will be explained in connection with Fig. 2. The figure shows a schematic representation of a temporal progression of the crimping depth A. The crimping depth correlates directly with a distance between the crimping rollers 32a, 32b, for example the distance between the rotational axes 34a, 34b, but with the opposite sign. This means that with decreasing distance between the rotational axes 34a, 34b, the crimping depth increases and vice versa. A zero point of the crimping depth can be set to the value at which cylinder shells constructed from the envelope curves of the crimping rollers just touch. With increasing meshing of the crimping rollers, the crimping depth assumes positive values. Fig. 2 shows the crimping depth A in arbitrary units over time t, also shown in arbitrary units.Instead of focusing on the time t, it would also be possible to focus on a position along the flat track 6, viewed in the material flow direction T.

[0069] Before time t1, the crimping rollers 32a, 32b are in the working position. In the working position, the crimping rollers 32a, 32b mesh with a crimping depth A1. In the working position, the crimping depth is controlled, for example, by feedback. At time t1, the control unit 30 receives the opening signal S. Based on the processing speed and the geometry of the material flow in the machine 2, the time t2 is determined at which the control unit 30 controls the adjustment means 36 such that the first crimping roller 32a begins the opening movement toward the disengagement position. The first crimping roller 32a is moved at high speed, referred to as the first travel speed, toward the disengagement position. This shows the steep gradient with which the crimping depth A decreases from time t2.

[0070] From time t3 onwards, the crimping depth A is so shallow that articles or intermediate products manufactured from a flat web 6 crimped to this depth, for example, paper filters 24 manufactured from the flat web 6, no longer meet the desired quality criteria. This limiting value of the crimping depth shall be referred to as crimping depth A3. From time t3 onwards, again taking into account the corresponding production speed and geometry of the material flow, the products manufactured from the corresponding area of ​​the flat web 6 are ejected. For example, the ejection unit 52 is controlled to eject paper filters 24 manufactured from the corresponding area of ​​the paper web 6.

[0071] Between time t4 and time t5, the splice passes through the pair of crimping rollers. At time t4, the first crimping roller 32a has not yet fully completed its opening movement toward the disengagement position. From time t5, the crimping rollers 32a have reached the crimping depth A2, which corresponds to the disengagement position. The time period until time t6, at which the closing movement begins and the first crimping roller 32a is moved back toward the working position, is dimensioned with a corresponding safety margin. This ensures with near certainty that the splice has passed through the pair of crimping rollers before the closing movement begins.

[0072] The closing movement takes place in a first section, which is first traversed starting from the disengagement position and occupies a predominant portion of the adjustment path 38 traversed during the closing movement, at a second travel speed. The first section extends between time t6 and time t7. The second travel speed can be similar to or equal to the first travel speed at which the first crimping roller 32a is moved toward the disengagement position between time t2 and time t5. The travel speeds are, in particular, constant over time, at least in sections.

[0073] At time t7, the crimp depth A again reaches the value A2. This value is characterized by the fact that articles produced from a flat strip crimped with the corresponding crimp depth meet the specified quality criteria. In other words, from time t7 onwards, the crimp depth A is again large enough to produce articles of the desired quality. Therefore, from time t7 onwards, the removal of articles from the production process can be terminated. The value A2 of this crimp depth can be determined, in particular, by the user of machine 2, for example, taking into account the respective quality criteria.

[0074] In a subsequent section of the closing movement, which begins at time t8, the first crimping roller 32a continues the closing movement at a third travel speed. This third travel speed is significantly lower than the first and second travel speeds. This results from an examination of the gradients of the time-dependent crimping depth in the respective sections (first travel speed: section t2 t5; second travel speed: section t6 t7; third travel speed: section t8 t9). In sections t2 to t5, the gradient of the crimping depth A and thus the travel speed are significantly higher than in sections t8 to t9. The gradient of the crimping depth in sections t6 to t7 is also significantly greater than in sections t8 to t9, since in the first section of the closing movement, the first crimping roller 32a is moved at a higher travel speed than in the second section of the closing movement. From time t9, the first crimping roller 32a has returned to its working position.

[0075] The entire opening movement extends between times t2 and t5, the entire closing movement extends between times t6 and t9. The first partial section of the closing movement, which takes place between times t6 and t7, extends between crimping depths A2 and A3. The second partial section extends between crimping depths A3 and A1. The adjustment path 38 extends from crimping depth A2 to crimping depth A1. As can be seen from a comparison of the intervals between A2 and A3 and between A3 and A1, the first partial section takes up the majority of the adjustment path 38 traversed during the closing movement. According to advantageous exemplary embodiments, the first partial section takes up at least 80%, in particular at least 85% and furthermore in particular at least 90% of the entire adjustment path 38 that extends between A2 and A1.

[0076] The transition between the first subsection and the second subsection is defined by an adjustment point at which the crimping depth has the value A3. This adjustment point can be changed depending on user input. The adjustment point, defined by the value of the crimping depth A3, can be determined, for example, depending on the quality criteria for the products manufactured from the crimped flat strip. Figs. 3 and 4 each show a simplified perspective view of an embodiment of the crimping station 26. According to the embodiment shown, the adjustment means 36 are designed such that they comprise a linear guide 40. With the aid of this linear guide 40, the first crimping roller 32a can be moved relative to the second crimping roller 32b. The second crimping roller 32b is, for example, fixedly mounted.The first crimping roller 32a is mounted on a support plate 42, which is coupled to the base plate of the crimping station 26 via the linear guide 40 for moving the first crimping roller 32a. The first crimping roller 32a and its first drive motor 44a are mounted on the support plate 42. The second crimping roller 32b is driven by a second drive motor 44b and is mounted on the base plate.

[0077] A travel motor 46 is provided for moving the first crimping roller 32a along the linear guide 40. In other words, the travel motor 46 is configured and designed to move the first crimping roller 32a, guided by the linear guide 40, along the adjustment path 38 (see also Fig. 1).

[0078] A rotary encoder 48 is coupled to the travel motor 46. A linear encoder 50 is coupled to the linear guide 40. The movement and position of the first crimping roller 32a along the adjustment path 38 can be measured using both the rotary encoder 48 and the linear encoder 50. The distance between the crimping rollers 32a, 32b, in other words also the crimping depth shown in Fig. 2, can be calculated from the measured values ​​of both encoders 48, 50. However, the measured values ​​of the linear encoder 50 are more precise. For this reason, the control unit 30 is set up and designed to feedback-regulate the opening movement, taking into account both the measured values ​​recorded by the rotary encoder 48 and the measured values ​​recorded by the linear encoder 50.In this context, it is particularly provided that the control unit 30 is configured and designed to regulate the closing movement in the first subsection, i.e., between the crimping depth A2 and the crimping depth A3, or between times t6 and t7, taking into account the measured values ​​acquired by the rotary encoder 48. In the second subsection, between the crimping depth A3 and the crimping depth A1, or between times t8 and t9, the movement of the first crimping roller 32a along the adjustment path 38 is regulated taking into account the measured values ​​acquired by the linear encoder 50. This makes it possible to move precisely to the working position.

[0079] All mentioned features, including those that can be inferred from the drawings alone, as well as individual features disclosed in combination with other features, are considered essential to the invention, both individually and in combination. Embodiments according to the invention may be fulfilled by individual features or a combination of several features.

[0080] List of reference symbols

[0081] 2 machines

[0082] 4 Provisioning unit

[0083] 6, 6' flat track

[0084] 8, 8' reel

[0085] 10 Splicing unit

[0086] 12 Crimping device

[0087] 14 Feed unit

[0088] 16 gathering units

[0089] 18 format unit

[0090] 20 paper filter strands

[0091] 22 cutting unit

[0092] 24 paper filters

[0093] 26 Crimping station

[0094] 28 detection unit

[0095] 30 Control unit

[0096] 32a first crimping roller

[0097] 32b second crimping roller

[0098] 34a first rotation axis

[0099] 34b second rotation axis

[0100] 36 adjustment tools

[0101] 38 adjustment range

[0102] 40 linear guide

[0103] 42 mounting plate

[0104] 44a first drive motor

[0105] 44b second drive motor

[0106] 46 Traversing motor

[0107] 48 rotary encoder

[0108] 50 linear encoders

[0109] 52 Discharge unit

[0110] T Material flow direction

[0111] L Longitudinal direction s Opening signal

[0112] A Crimp depth t Time

Claims

Device and method for crimping a flat strip and machine for producing paper filters Patent claims 1. A device (12) for crimping a flat web (6) made of a material from the tobacco processing industry, comprising a crimping station (26) with a first crimping roller (32a) rotatably mounted about a first rotational axis (34a) and with a second crimping roller (34b) rotatably mounted about a second rotational axis (34b), which are operatively coupled and configured to produce a plurality of longitudinal lines in the flat web (6) as it passes between the crimping rollers (34a, 34b), along which lines the flat web (6) is easily foldable, in particular in its transverse direction, characterized by: a detection unit (28) configured and designed to detect a splice point and / or an increase in the material thickness of the flat web (6) that is spatially limited in the longitudinal direction (L) of the flat web (6) and that exceeds a predeterminable limit value, and to generate an opening signal (S) in response thereto,wherein the detection unit (28) is arranged upstream of the crimping station (26) in the material flow direction (T), Adjustment means (36) which are configured and designed to move at least one of the two crimping rollers (32a, 32b) along an adjustment path (38) between a working position, in which longitudinal lines are generated in the flat web (6) when the flat web (6) passes between the crimping rollers (32a, 32b), and a disengagement position relative to one another, wherein a distance between the first and second rotation axes (34a, 34b) is smaller in the working position than in the disengagement position, a control unit (30) coupled to the detection unit (28) and the adjustment means (36), which is configured and designed such that the adjustment means (36), in response to the opening signal (S), move the at least one crimping roller (32a, 32b) in an opening movement towards the disengagement position, and move the at least one crimping roller (32a, 32b) in a closing movement towards the working position,and execute the closing movement in two mutually different sections of the adjustment path (38) at mutually different travel speeds. Device (2) according to claim 1, characterized in that the closing movement takes place from the disengagement position to the working position, wherein the control unit (30) is configured and designed to control the adjustment means (36) such that the closing movement is performed at a second, in particular temporally constant, travel speed in a first partial section, which is first traversed starting from the disengagement position and occupies a predominant portion of the adjustment path (38) traversed during the closing movement, and the closing movement is performed at a third, in particular temporally constant, travel speed in a second partial section, which is traversed subsequent to the first partial section.wherein the third travel speed is lower than the second travel speed., Device (2) according to claim 2, characterized in that the opening movement takes place starting from the working position up to the disengagement position, and the control unit (30) is designed and configured to control the adjustment means (36) such that the opening movement is performed at a first, in particular temporally constant, travel speed in a partial section that occupies the at least predominant part of an adjustment path (38) traversed during the opening movement, wherein the third travel speed is lower than the first travel speed and the third travel speed is lower than the second travel speed. Device (2) according to claim 3, characterized in that the first travel speed is greater than or equal to the second travel speed.Device (2) according to one of claims 2 to 4, characterized in that the first sub-section occupies at least 80%, in particular at least 85%, furthermore in particular at least 90% of the adjustment path (38) traversed during the closing movement. Device (2) according to one of claims 2 to 4, characterized in that the control unit (30) is designed and configured to change an adjustment path point at which the transition between the first and the second sub-section takes place, wherein the control unit (30) is designed and configured to change the adjustment path point depending on a parameter received as part of a user input. Device (2) according to one of claims 1 to 6, characterized in that the adjusting means (36) comprise a linear guide (40) and at least one travel motor (46), wherein the travel motor. (46) is set up and designed to move the at least one crimping roller (32a, 32b), guided by the linear guide (40), along the adjustment path (38), wherein the adjustment means (36) further comprise a rotary encoder (48) coupled to the travel motor (46) and a linear encoder (50) coupled to the linear guide (40), with each of which an adjustment of the at least one crimping roller (32a, 32b) along the adjustment path (38) can be measured, wherein the control unit (30) is further set up and designed to feedback-regulate the opening movement taking into account the measured values ​​detected by the rotary encoder (48) and to feedback-regulate the closing movement taking into account the measured values ​​detected by the rotary encoder (48) and the linear encoder (50).

8. Device (2) according to claim 7 in conjunction with one of claims 2 to 6, characterized in that the control unit (30) is set up and designed to control the closing movement in the first subsection taking into account the measured values ​​detected by the rotary encoder (48) and in the second subsection taking into account the measured values ​​detected by the linear encoder (50).

9. Device (2) according to one of claims 1 to 8, characterized in that the detection unit (28) comprises at least one sensor which is designed and configured to measure the material thickness of the flat web (6), wherein the sensor is in particular an optical sensor, furthermore in particular the sensor is designed and configured to measure a translucency of the flat web (6).

10. A method for crimping a flat web (6) made of a material from the tobacco processing industry, comprising the following steps: providing a flat web (6) and feeding the flat web (6) to a crimping station (26), Creating a plurality of longitudinal lines in the flat web (6), along which the flat web (6), in particular in its transverse direction, is easily foldable by passing the flat web (6) in the crimping station (26) between a first crimping roller (32a) rotating about a first rotational axis (34a) and a second crimping roller (32b) rotating about a second rotational axis (34b), characterized by the following steps: Detecting a splice point and / or a spatially limited increase in the material thickness of the flat web (6) in the longitudinal direction of the flat web (6) which exceeds a predeterminable limit value, in response thereto, generating an opening signal (S), with a detection unit (28) which is arranged upstream of the crimping station (26) in the material flow direction (T), in response to the opening signal (S), moving the at least one crimping roller (32a, 32b) in an opening movement in the direction of a disengagement position, Moving the at least one crimping roller (32a, 32b) in a closing movement towards the working position, wherein the closing movement is carried out in two mutually different sections of an adjustment path (38) with mutually different travel speeds, wherein the movement of the crimping rollers (32a, 32b) is carried out by means of adjustment means (36) which are designed and constructed to move at least one of the two crimping rollers (32a, 32b) along an adjustment path (38) between the working position, in which longitudinal lines are generated in the flat web (6) when the flat web (6) passes between the crimping rollers (32a, 32b), and the disengagement position relative to one another, wherein a distance between the first and the second rotational axes (34a, 34b) is smaller in the working position than in the disengagement position. Method according to claim 10, characterized in that the closing movement between the disengagement position and the working po- sition, wherein the closing movement is carried out at a second, in particular temporally constant, travel speed in a first partial section, which is first traversed starting from the disengagement position and takes up a predominant part of the adjustment path (38) traversed during the closing movement, and the closing movement is carried out at a third, in particular temporally constant, travel speed in a second partial section, which is traversed subsequently to the first partial section, wherein the third travel speed is lower than the second travel speed.Method according to claim 11, characterized in that the opening movement takes place between the working position and the disengagement position, wherein the opening movement is carried out in a partial section which takes up at least the predominant part of an adjustment path (38) traversed during the opening movement, at a first, in particular temporally constant, travel speed, wherein the third travel speed is lower than the first travel speed and the third travel speed is lower than the second travel speed. Method according to claim 12, characterized in that the first travel speed is greater than or equal to the second travel speed. Method according to one of claims 11 to 13, characterized in that the second partial section takes up at least 80%, in particular at least 85%, furthermore in particular at least 90% of the adjustment path (38) traversed during the closing movement.Method according to one of claims 11 to 13, characterized in that an adjustment path point is changed at which the. Transition between the first and the second subsection takes place, wherein the adjustment path point is changed in particular depending on a parameter received as part of a user input.Method according to one of claims 10 to 15, characterized in that the adjustment means (36) comprise a linear guide (40) and at least one displacement motor (46), wherein the displacement motor (46) moves the at least one crimping roller (32a, 32b), guided by the linear guide (40), along the adjustment path (38), wherein the adjustment means (36) further comprise a rotary encoder (48) coupled to the displacement motor (46) and a linear encoder (50) coupled to the linear guide (40), with each of which an adjustment of the at least one crimping roller (32a, 32b) along the adjustment path (38) is measured, wherein the opening movement is controlled with feedback taking into account the measured values ​​detected by the rotary encoder (48) and the closing movement is controlled with feedback taking into account the measured values ​​detected by the rotary encoder (48) and the linear encoder (50).Method according to claim 16 in conjunction with one of claims 11 to 15, characterized in that the closing movement is controlled with feedback in the first subsection, taking into account the measured values ​​acquired by the rotary encoder (48), and in the second subsection, taking into account the measured values ​​acquired by the linear encoder (50). Method according to one of claims 10 to 17, characterized in that the detection unit (28) comprises at least one sensor, wherein the sensor measures the material thickness of the flat web (6), and wherein the sensor is in particular an optical sensor, which further measures in particular a translucency of the flat web (6). Machine (2) for producing paper filters (24), comprising: a supply unit (4) for providing a flat web (6) made of a paper material from the tobacco processing industry, a device (12) for crimping the flat web (6) according to one of claims 1 to 10, a feed unit (14) which is designed and configured to feed the flat web (6) to the device (12) for crimping, a gathering unit (16) which is designed and configured to gather the crimped flat web (6) transversely to its longitudinal direction, a format unit which is designed and configured to produce a paper filter strand (20) from the gathered, crimped flat web (6), and a cutting unit (22) which is designed and configured to cut paper filters (24) to length from the paper filter strand.Machine (2) according to claim 19, characterized by a discharge unit (52) designed and configured to discharge paper filters (24) produced from the paper filter strand (20) from the ongoing process, wherein the control unit (30) of the crimping device (12) is further configured to trigger a discharge process of the discharge unit (52) in response to the opening signal (S) of the detection unit (28). Machine (2) according to claim 20, characterized in that the control unit (30) is further configured and configured to synchronize the opening movement with the opening signal (S) in such a way that the splice point and / or the increase in the material thickness of the flat web (6) passes through the crimping rollers (32a, 32b) before the opening movement is completed.

Images