EP2238847B1 - Method for operating a filter rod machine and filter rod machine - Google Patents

Description

description

The invention relates to a method for operating a filter rod machine of the tobacco processing industry, wherein filter material in the form of a strip of filter material taken from a supply in the form of at least one bale, spread, stretched, conveyed by an applicator and a formatting device of the filter rod machine is fed and from the filter material strip Filter strand is formed. The invention further relates to a filter rod machine of the tobacco-processing industry with a filter material dispensing station, from which a filter material strip of at least one filter material supply can be dispensed, with a stretching device and / or a spreading device, an applicator and a strand forming device by means of the filter material strip a filter strand can be produced, wherein at least one sensor is provided which is configured to detect a defect of the filter material strip.

In particular, connection points between successive filter material strips (also called "toows") and so-called "tow-twists" come into question as defects. A common method for producing joints between filter material strips is the overlapping of the ends of the filter material strips and the welding by means of heat, in which the fibers, for. As acetate fibers, merge. The weld forms a hardening in the otherwise soft material flow.

Tow-Twists are locations of the filter material strip, where it is turned over its longitudinal axis by 180 °. Tow-twists can occur when removing the strip of filter material from the bale and represent a defect, since they have different properties after processing than the rest of the filter material. For example, when sprayed at the location of a tow twist, the filter material strip absorbs less plasticizer because of its reduced surface area.

A method and a device for producing filter rods for smokable articles are known, for example, from US Pat DE 32 24 009 A1 known. In this document it is disclosed that the end of the expiring filter tow is connected to the beginning of a filter tow contained in a second bale. The connection point is stored and recorded on a detector means in good time before the end of the filter screen contained in the first bale. The outgoing end of the filter tow drawn off from the first bale lifts the connection point away from the detector means, which thereby generates a corresponding control signal. The control signal is used to adjust the conveyer and treatment equipment passed by the filter tow to the passage of the thicker joint for reducing the machine speed and / or used to eject the filter rod containing the joint.

One opposite DE 32 24 009 A1 further developed method and a corresponding device for operating a filter rod machine of the tobacco processing industry is out DE 10 2005 062 091 A1 the applicant known. In the method mentioned therein, the end of a filter material strip of a first bale is also connected to the beginning of a filter material strip of a second bale at a connection point and fed to a filter strand production machine. After the production of the filter strand, a sensor arranged in the conveying direction of the filter strand downstream of the strand forming device recognizes the connection point and generates a signal which serves to exclude at least the region of the filter strand which has been produced from the filter material strip with the connection point from further processing ,

EP 1 754 418 A1 relates to a method and a device for supplying an additive to a filter material web, wherein a width measuring device is arranged immediately upstream of a device with spray nozzles. By means of the width measuring device, the width of the filter material is measured and regulated by a sliding cover plate, the amount of the applied additive.

EP 1 649 764 A1 relates to a filter manufacturing method and a corresponding device for applying plasticizer to filter material, wherein a measuring device is provided for generating a signal which is at least in the conveying direction of the Filter material represents spatially resolved concentration of the plasticizer in the filter material. Upstream of a feeder for feeding triacetin as well as a pair of rollers forming part of a stretching device, transducers, light sources and photoelectric detectors are arranged to separately measure density values of the web material in different areas to detect inhomogeneities and then the triacetin coating to control.

EP 1 106 087 A2 relates to a method and apparatus for feeding a preferably liquid additive to a moving web of expanded filamentary filter material. Upstream of a nozzle for applying triacetin and a pair of rollers of a stretching device, the density of the web strip is measured by means of transducers with light sources and photoelectric detectors, and then the amount of triacetin fed is controlled.

With the known methods and devices it is not possible to detect tow-twists.

It is an object of the present invention to provide a method for operating a filter rod machine of the tobacco processing industry and a corresponding filter rod machine, by means of the least possible filter material committee a filter strand with high quality can be produced, and with the particular tow-twists as defects of a filter material strip can be recognized.

This object is achieved by a method for operating a filter-strand machine the tobacco-processing industry, wherein filter material in the form of a strip of filter material taken from a supply in the form of at least one bale, spread, stretched, promoted by an applicator and a format device of the filter rod machine is fed and from the filter material strip a filter strand is formed, which is further developed in that at least one sensor recognizes a defect after stretching the filter material strip and before the application device and generates at least one signal which serves to exclude at least the region of the filter strand having the defect from further processing.

The arrangement of the sensor for detecting defects after stretching and spreading of the filter material strip and before the applicator has the advantage that it is much more accurate than previously possible to detect the area of the filter strand or to identify those filter rods that are to be ejected, because the area or the filter rods contains or contain a defect.

The filter material strip has its greatest width after the spreading of the filter material strip. Defects are exposed on the spread filter material strip and are directly and immediately recognizable. Thus, a more direct and secure detection of a defect is possible as downstream after the passage of a format device to which a detection of defects under certain circumstances is only indirectly possible. The position of the sensor after stretching has the further advantage that the not exactly calculable length changes by the stretching of the filter material strip and the transport of the filter material strip from the filter material strip supply to the filter strand manufacturing machine has already taken place. Downstream of the stretching device, the speed of the material flow is very accurately known and subject no more significant fluctuations. This makes it possible to limit the area of the filter material strip or the filter rods produced therefrom to about 5 to 6 filter rods, namely about two filter rods in front of the affected area, the affected filter rod and two to three filter rods after the affected area.

In modern production facilities, there are distances between the location of the filter material strip bales, possibly in a so-called "bale yard", and the filter rod machine of up to 20 m, through which the filter material is conveyed in channels or in tube systems. In the case of the very elastic filter material strip, during this transport a certain amount of pre-stretch occurs, which takes place unevenly over the length of the filter material strip. Therefore, the position of a joint in the produced filter strand is only very imprecisely predictable, if they are in accordance with DE 32 24 009 A1 was detected only at the location of the filter material strip supply. In this prior art, about 100 filter rods are shot out to safely eject a filter rod affected by a joint. Positioning the sensor in front of the applicator protects the sensor from contamination with coating material, such as droplets of plasticizers.

Preferably, the defect is recognized as a waist of the strip of filter material caused by a joint in the strip of filter material at which the end of the strip of filter material of a first bale is connected to the beginning of the strip of filter material of a second bale or by a 180 ° turn of the strip of filter material about its longitudinal axis becomes (tow-twist). Both the tow-twist and the joint lead to a waist of the filter material strip. The connection point resists expansion with its stiff weld. Under a sidecut in the context of the invention, a taper or constriction understood.

In the case of a joint is a thickening of the filter material strip because of the superimposed ends of two assembled filter material strips. Therefore, the defect is detected in an advantageous embodiment by means of an acoustic signal, which arises when the defect is guided on a drum with a metallic surface along. Since the defect is thickened and conveyed past the drum at high speed, it strikes the metal drum as a bell is struck by a clapper. The acoustic vibration of the drum is recorded by an acoustic pickup and detected in an evaluation device. The metal drum may be part of the last, that is downstream, drum pair of a stretching device, which is composed of two consecutive pairs of drums.

Further preferably, the malposition is determined by means of an acceleration sensor. An acceleration sensor in one embodiment has a spring-assisted arm over which the strip of filter material is passed. In the case of a defect, in particular a thickening or compression of the strip of filter material due to a connection point, the strip of filter material currently exerts an increased force on the lever arm and deflects it for a short time. The acceleration that occurs during the short-term deflection is registered by the acceleration sensor, so that the defect is detected.

In a particularly preferred embodiment of the method according to the invention it is provided that the defect by means of a optical transmission and / or Auflichtverfahrens is determined, wherein the amount of the transmitted and / or the reflected light is detected along at least part of the width of the filter material strip. Since the filter material strip has the greatest width after stretching and before the application device, the defect, in the form of a connection point or a tow twist, emerges openly and can be reliably detected by optical means in a transmitted light and / or incident light method. Transmitted light or incident light methods are also referred to as transmission or reflection methods.

Since both a connection point and a tow-twist is associated with a narrowing or waisting of the filter material strip, it is provided in a particularly simple development that at least one edge of the filter material strip is detected and in particular a region of the center of the filter material strip is detected. The change in the optical signal in the edge region of the strip of filter material signals a waisting of the strip of filter material and allows a conclusion about a defect. A waisting leads to an increase in the edge area in the transmitted light method and in the incident light method to a reduction in the registered amount of light.

In the middle of the strip of filter material, a tow-twist leads to a doubling of the material thickness in sections, so that a reduction in the transmitted amount of light occurs in the transmitted-light method, while stronger reflection occurs in the incident-light method.

In the case of joints, it has been found that the weld ruptures upon expansion and the strip of filter material disintegrates into a plurality of narrow fiber bundles, the fibers of which are each separated by a fragment of the original weld held together. Since the subsequent stretching along the width of the filter material strip has a different effect, resulting over the width of the filter material strip compact and spaced by wide gaps spliced fiber bundles. The resulting gaps lead to an increase in the transmitted light in the transmitted light method and a decrease in the reflection in incident light. Due to the different stretching the fragments of the weld in the conveying direction are arranged staggered by up to several centimeters. This too can be detected by optical means.

It is preferably provided that the filter material strip is scanned at regular intervals, in particular at intervals between 2 and 10 mm, in particular between 4 and 6 mm. By this measure, the morphology and thus the nature of the defect is clearly recorded. Advantageously u. a. the recognition accuracy increased by the use of at least two, in particular different, sensors, at the position according to the invention.

Preferably, the signal of the sensor is used to lower the conveying speed of the filter material strip. As a result, the filter rod machine and the corresponding components in the filter rod machine, through which the filter strand and thus the defect run, spared.

The object underlying the invention is also achieved by a filter rod machine of the tobacco processing industry with a Filtermaterialabgabestation from which a strip of filter material of at least one filter material supply can be delivered with a spreading device, a stretching device, an applicator and a strand forming device, by means of the Filter strip is produced, wherein at least one sensor is provided, which is designed to detect a defect of the filter material strip, wherein the sensor at the location or downstream of the stretching device and upstream of the applicator is arranged, wherein further comprises an evaluation device for evaluating a signal the sensor is provided for the presence of a defect of the filter material strip. The inventively designed filter rod machine has the advantage described above that defects such as tow-twists or joints at the point of maximum spread of the filter material strip open to light days and be reliably recognized and due to the well-defined course of promotion downstream of the stretching device, the Committee is kept low. The arrangement in front of the application device also contamination of the optical sensors by application material, such as plasticizers, is avoided.

Further preferably, a, in particular in the evaluation integrated control means is provided by means of, in particular by means of a presettable and / or dependent on the conveying speed of the filter material strip timer or a shift register, an ejection of a defect detected defective filter strand sections or filter rods and / or a Lowering the conveying speed of the filter material strip is controllable.

In an advantageous embodiment, the sensor comprises a drum with a metallic surface, over which the filter material strand is guided, wherein the drum is connected to an acoustic pickup. A defect, especially a thickened joint, causes the metallic drum to vibrate when hitting the drum surface. The vibration is picked up by an acoustic pickup and recognized in an evaluation device. Alternatively or additionally, a sensor is preferably designed as an acceleration sensor, in particular as a lever, over which the filter material strip is guided.

In a particularly preferred embodiment, the sensor comprises a photosensitive sensor aligned with a surface of the strip of filter material and spaced from the strip of filter material. The photosensitive sensor preferably detects at least part of the width of the filter material strip, in particular at least one edge and in particular a region of the center of the filter material strip. The distance between the sensor and the strip of filter material is preferably between 30 and 200 mm, in particular between 80 and 120 mm.

Advantageously, the sensor comprises a light-sensitive receiving element, which is aligned in particular at an angle of approximately 90 ° to the conveying direction of the filter material strip. By means of the photosensitive receiving element results in a good spatial resolution, so that the nature of a defect, such as a tow-twist or a junction is detected. Advantageously, the use of glass optical fiber lines is provided as a sensor head, which forward the received light to a photosensitive receiving element. A glass optical fiber line is resistant to abrasion against the filter material strip, so that under certain circumstances it can also be guided over the optical waveguide line and thus undergoes self-cleaning. The photosensitive receiving element may be a CCD line by way of example.

For the optical recognition method is preferably a light source, in particular an optical fiber line, provided, which is arranged on the side opposite the sensor of the strip of filter material, or which is arranged on the same side of the strip of filter material as the sensor, wherein in particular a reflector on the side opposite the sensor side of the filter material strip is arranged. The first alternative mentioned is an arrangement for a transmitted light method, the second alternative for an incident light method, wherein elements of a transmission method (with double absorption) are recorded by the provision of a reflecting surface or a mirror on the opposite side. The reflective surface can serve as a light source by the reflection of ambient light.

For better detection of imperfections it is also envisaged to use two or more sensors, which in particular are based on different measuring principles and / or at least partially observe different regions of the filter material strip.

Finally, the object underlying the invention is achieved by the use of at least one sensor for detecting defects of a filter material strip in the form of a junction of interconnected filter material strips of different bales or in the form of a 180 ° rotation of the filter material strip about its longitudinal axis in a filter rod machine of tobacco processing The industry as described above, wherein the sensor is located at or downstream of the stretching device and / or the expanding device and upstream of the applicator.

In particular, by using a further sensor in the edge region of the strip of filter material, a further improved discrimination between defects caused by a tow-twist and defects caused by a connection point. The use of several sensors also increases the redundancy and thus the detection reliability of the measurement.

Fig. 1

eine schematische Seitenansicht einer Ausführungsform einer erfindungsgemäßen Filterstrangmaschine,

Fig. 2

eine schematische Ansicht eines Teils eines Filtermaterialstreifens mit Verbindungsstelle nach dem Aufweiten des Filtermaterialstreifens,

Fig. 3

eine schematische Ansicht eines Teils eines Filtermaterialstreifens mit einem Tow-Twist,

Fig. 4

eine schematische Darstellung eines Querschnitts durch eine erfindungsgemäße optische Sensoranordnung,

Fig. 5

eine schematische Darstellung eines Querschnitts durch eine weitere erfindungsgemäße optische Sensoranordnung,

Fig. 6

eine schematische Seitenansicht einer erfindungsgemäßen akustischen Sensoranordnung und

Fig. 7

eine schematische Seitenansicht einer erfindungsgemäßen Sensoranordnung mit einem Beschleunigungssensor.

The invention will be described below without limiting the general inventive idea by means of embodiments with reference to the drawings. With respect to all details of the invention not explained in detail, reference is expressly made to the drawings. Show it:

Fig. 1

a schematic side view of an embodiment of a filter rod machine according to the invention,

Fig. 2

a schematic view of a portion of a filter material strip with connection point after the widening of the filter material strip,

Fig. 3

a schematic view of a portion of a filter material strip with a tow-twist,

Fig. 4

a schematic representation of a cross section through an optical sensor arrangement according to the invention,

Fig. 5

a schematic representation of a cross section through a further inventive optical sensor arrangement,

Fig. 6

a schematic side view of an acoustic sensor assembly according to the invention and

Fig. 7

a schematic side view of an inventive Sensor arrangement with an acceleration sensor.

Fig. 1 shows a schematic side view of an embodiment of a filter rod machine according to the invention, comprising a treatment device 1 and a processing device 2. The filter rod machine, a filter rod 24 is prepared for example for the production of filter rods 28 for cigarettes and other smokable articles. The illustrated device for producing filter rods 28 may, for example, be a model of the product line KDF marketed by the applicant. The device consists of two main assemblies, a processing device 1 for filter tow supplied in an endless filter material strip 4 and a processing device 2 for producing wrapped filter rods 28.

The processing device 1 has a pair of rollers 3 for the continuous removal of an endless filter material strip 4 from a bale 6. After removal from the bale 6 of the filter tow 4 passes on its up to 20 m long path to the pair of rollers 3, on which it is guided over a guide roller 5 and through a channel system, not shown, two air nozzles 7 and 8, for spreading and loosening of the tissue serve the filter material strip 4.

In the direction of movement of the strip of filter material 4 after the air nozzle 8 and before the pair of rollers 3 is serving as an air conditioning device for the filter material strip 4 climatic chamber 10 through which the filter material strip 4 is passed. In the climatic chamber 10, the filter material strip 4 is supplied with water vapor from a water vapor source 10a or dry hot air from a hot air source 10b. For regulation the humidity of the filter material strip 4 can regulate the humidity in the climate chamber 10 by the supply of water vapor can be controlled by means of one of a control or regulating device 43 according to arrow 10e or control line 10e controllable control valve 10c, while the supply of dry hot air can be controlled by means of a controllable by the control or regulating device 43 via the control line 10f control valve 10d.

After the climatic chamber, a pre-stretching roller pair 13 provided with a drive controllable by a control 14 is arranged to pre-stretch the filter material strip 4. The stretching of the filter material strip 4 to eliminate the so-called residual crimp in the strip of filter material is done by deflecting the strip of filter material 4 from its movement path through a dancer roller 15. The dancer roller 15 is acted upon via a controllable by the controller 14 actuator 16 with a defined force, so that the Tensile stress in the filter material strip 4 between the Vorreckwalzen 13 and the roller pair 3 assumes a desired predetermined value. As a result, the residual crimp in the strip of filter material 4 is pulled smoothly. This results in a variable extension of the filter material strip 4, whereby the position of the dancer roller 15 changes. The position of the dancer roller 15 is measured by the controller 14 via the actuator 16 and controlled by controlling the conveying speed of the Vorreckwalzen 13 to a constant value. To this is on the DE 101 52 162 A1 referred to the applicant.

The roller pair 3 is followed by two further roller pairs 9 and 11. All roller pairs 3, 9 and 11 are driven individually. The speed of the roller pair 9 substantially corresponds to the conveying speed in the processing device 2. The speed of the roller pair 3 is smaller than that of the roller pair 9, so that the Roll pairs 3 and 9 form a stretching device for the material strip 4. By stretching the mass of the filter tow is determined in the finished filter rods 28, whereby the mass can be adjusted by controlling the conveying speed of the first pair of rollers 3. The speed of the roller pair 3 can be controlled by a control or regulating device 43 according to the control line 3a.

Between the pairs of rollers 9 and 11 is an applicator 12 for applying a plasticizer, such as triacetin, on the guided between the roller pairs 9 and 11 guided filter material strip 4. The supply of the plasticizer to the applicator 12 by means of a metering pump 33 via a supply line 34 from a softener supply 36. The metering pump 33 can be controlled by the control or regulating device 43 via a control line 33a.

The processed, sprayed with plasticizer strip of filter material 4 passes over the pair of rollers 11 of the processing unit 1 in an inlet hopper 17 of the housing 2a having a processing device 2, in which he summarized and on a deducted from a reel 18 and by means of a glue nozzle having Beleimvorrichtung 19 with Glue provided wrapper strip 21 is placed. The wrapping strip 21 and a filter material strand 4a formed by combining the filter material 4 reach a format strip 22 which guides both components through a format 23 which wraps the wrapping strip 21 around the filter material bar 4a and forms an endless filter strand 24. The speed of the format tape 22 is controlled by a main controller 25 via a control line 25a and to the also of the main controller 25 by controlling the drives of the roller pairs 9 and 11 according to the Control lines 25b and 25c certain conveying speed of the stretched filter Tert 4 tuned.

The filter strand 24 passes through cooling webs 26, in which the hot glue seam is cooled. Subsequently, filter rods 28 are cut off continuously from the filter strand 24 by means of a knife apparatus 27, which are transferred by an accelerator 29 into a discharge drum 31, in which they are conveyed in the transverse-axial conveying direction. From the Ablegertrommel 31 enter the filter rods 28 to a Ablegerband 32, from which they are fed to a further processing or intermediate storage or excluded from further processing by an ejector, not shown.

Downstream of the cooling webs 26 and upstream of the knife apparatus 27, an optional first and second measuring device 37, 38 are arranged, which can separately detect the proportions of the components of the strand 24, namely dry filter tow, plasticizer and water. The second measuring device 38 comprises a microwave measuring system with a measuring head with a microwave source and a microwave detector, which detects the microwaves emanating from the microwave source and penetrates the filter strand 24 to generate and deliver two measured values 38a and 38b to the evaluating device 42. These measurements allow, for example, a statement about the water content and the common proportion of the chemically similar components plasticizer and filter tow in the filter strand 24. A suitable measuring method and a corresponding device are, for example, from EP 0 791 823 A2 to be taken from the applicant.

The measuring frequency of the optional measuring device 37 may be in the range of radio or microwaves or in the optical or in the infrared Area lie. When using wavelengths in the infrared range, the first measuring device 37 comprises an optical measuring head with an infrared radiation source and an infrared detector, which detects the emanating from the infrared radiation source, the filter strand 24 penetrating infrared waves. The intensity of the infra-red light penetrating the filter strand 24 is not influenced by a proportion of plasticizer in the filter strand 24, so that the infrared detector emits an evaluation signal to the evaluation device 42 via an amplifier which corresponds only to the proportion of the dry filter tow material in the filter strand 24. As a result, about a connection point 45, which can be detected by connecting the end of the filter strand 4 from the bale 6 with the beginning of the filter strand 4 ', which is made from the bale 6'.

Instead of the infrared measuring head of the measuring device 37, a measuring head can be used which operates with microwaves. This may be a cavity resonator, which is acted upon by only one frequency act. For measuring in the range of radio waves, for example, a nuclear magnetic resonance measurement can be provided, in which the magnetic moments of the atomic nuclei of the substance to be measured are aligned by an external magnetic field and then excited by radio waves in an energetically higher state in which they are substantially parallel to the external magnetic field are oriented. A possible embodiment of such a measuring device, for example, the DE 33 12 841 A1 taken from the applicant.

In order to enable an efficient and filter material-friendly transition from a bale 6 to a bale 6 'is, in particular according to Fig. 1 , proceed as follows. First, the end of the filter material strand 4 of the bale 6, for example, in a Connecting device 48 connected to the filter material strip 4 'of the bale 6', so that there is a connection point 45, for example, twice as much filter material as the filter material strips 4 and 4 '. A connection can be made, for example, with an adhesive.

By continuous removal of the filter material strip 4 by the guide ring 49 in the processing device 1, the bale 6 is reduced or shrinks this existing in the bale 6 material more and more. By means of an optical sensor 46, which may be a camera, for example, is detected in the detection direction 47, when the last layer of filter material strip 4 is reached in the bale 6 or when the last layer of the filter material strip 4, the area was deducted in the detection 47th of the optical sensor 46 is located. At this moment, a signal is supplied to the main controller 25 via a signal line 46a, for example. Then, the speed of the filter rod machine is reduced immediately or with a predetermined time delay, which is particularly dependent on the speed of removal of the filter material strip 4. It is also the components through which the filter material strip 4 passes, are at least partially pulled apart, so that the components of the filter rod machine are spared by the reduced speed and also the pulling apart of these components. A corresponding signal may also be supplied to the main control 25 from a third sensor 48 ', which represents the removal of the connection point 45 from this sensor.

The joint 45 then passes through the filter rod machine and in particular the processing device 1 and the processing device 2 and is in the format 23 of a Envelope material strips 21 wrapped and formed into a filter strand 24. The measuring device 37 can then be designed as above in order to detect the moment in which the filter strand has the connection point 45. This signal can then be used to exclude this area of the filter strand from further processing and / or to increase the speed of the filter rod machine again to a higher predefinable value. It may also be useful to exclude the portion of the filter string from further processing made during the slower operation of the filter rod machine.

In addition to this DE 10 2005 062 091 A1 known method and measuring system according to the invention now at least one sensor 39 between the stretching device from the roller pairs 9 and 11 and the applicator 12 is provided. At this point, the filter material strip 4 is maximally widened and imperfections, for example, connection points or tow-twists, are optimally revealed and can be easily and reliably recognized, for example, by optical means. The sensor 39 sends upon detection of a defect via a signal line 39a a signal to the evaluation device and control or regulating device 42, 43 and / or via a signal line 39b to the main controller 25. The signal 39a or 39b emitted by the sensor 39 is due to the process Automation functions used, for example, to reduce the speed of production and ejection of flawed filters.

Compared with the measurement by the sensor 37, this has the advantage that a direct detection of a defect is much easier and safer possible than after strand formation at the location of the sensor 37, where only an indirect measurement is possible. simultaneously is compared to the measurement at the location of the sensor 46, the remaining variation of the transit time between the sensor 39 and the Ablegertrommel 31 and the Ablegerband 32 reduced by a multiple, so that the Committee is significantly lower. There is an approximately constant shift register length until ejection. Since the sensor 39 is arranged upstream of the applicator 12, no or only little contamination with application material, eg triacetin, is to be expected on the optical interfaces of the sensor 39. As optical sensors known incident light and transmitted light sensors can be used, which can be integrated into production machines without structural changes, except for a holder to be inserted. At the point provided according to the invention, there is sufficient space in many filter rod machines, so that existing filter rod machines can be retrofitted with sensors 39 at the corresponding point.

In Fig. 2 a section of a filter material strip 4 with connection point after the widening of the strip of filter material is shown schematically. The connection point is a weld in which the ends of two successive filter material strips of two different bales 6, 6 'are superimposed and welded together. The weld remains intact during the conveyance of the strip of filter material 4 until its spreading and stretching. During the spreading and stretching of the strip of filter material, the seam bursts into small fragments 51 - 51 ^VII . This results in a bundle of fiber strands 50 - 50 ^VII , which are held together by a fragment 51 - 51 ^{VII of} the original seam. The fragments 51 - 51 ^VII appear in Fig. 2 as dark densified areas where the individual bundles 50-50 ^{VII are} tapered. In particular at the seams 51 - 51 ^VII , the distance between the individual bundles 50 - 50 ^{VII is} particularly large. This spliced signature of the filter material strip 4 is optical good to see.

In Fig. 2 is also shown that the individual fragments 51 - 51 ^VII are pulled apart due to the uneven stretching in the conveying direction 52 and compared to the original connection point by up to several centimeters or run behind. The bundle 50 ^IV has in the region of the illustrated section of the filter material strip 4 at all no connection point. This runs even further before or after. From this it is clear that the detection of defects downstream of the filter strand production is also problematic because the original joint is not located at a point in the filter strand after spreading and stretching the strip of filter material, but the fragments of the seam can extend over several centimeters. That at the location of the sensor 37 in Fig. 1 occurring signal can be weak in such cases and ensure no reliable detection of a junction.

A typical tow-twist 55 is shown schematically in FIG Fig. 3 shown. The filter material strip 4 has an axis of symmetry or longitudinal axis 56, which is shown in phantom. Symmetrically, the lower edge 53 and the upper edge 54 of the filter material strip 4 are shown. In the area of the tow-twist, a waist 55 of the filter material strip 4 results due to the fact that the filter material strip 4 turns over its longitudinal axis 56 by 180 °. The upper edge 54 of the strip of filter material 4 thereby extends to the viewer on the upper side of the strip of filter material, moves over the longitudinal axis 56 (line 54 ') and becomes the lower edge 53 "of the strip of filter material Contemplation level below the upper edge 54 'as a dashed line 53' over the longitudinal axis 56 and the upper edge 54 ".

Also shown in Fig. 3 a sensor 39 'which covers the area of the filter material strip 4 from the center, ie the longitudinal axis 56, to above the upper edge 54. He is therefore able to detect a constriction 55 due to a tow-twist or a connection point. On the opposite side of the constriction there is schematically illustrated a sensor 39 "which spans the entire width of the strip of filter material 4 and thus is capable of monitoring both edges 53, 54 of the strip of filter material 4 and the center of the strip of filter material 4. From each the two sensors 39 ', 39 "individually or the combination of both sensors can detect the occurrence and nature of a defect, such as a constriction 55 due to a tow twist, or a defect due to a connection point. A tow-twist can be made at the location of the sensor 37 Fig. 1 can not be detected because the density of the already formed filter material strand does not change when a tow twist occurs.

Fig. 4 schematically shows a cross section through an inventive optical sensor arrangement 60 for a transmitted light method. This has an optical sensor strip 61 and a strip-shaped light source 62, which are arranged on opposite sides of a strip of filter material 4. The light source 62 emits in the direction of the sensor bar 61 visible or infrared light, which penetrates the filter material strip on the way to the sensor bar 61. In a tow-twist, the transmitted amount of light increases because of the waisting of the strip of filter material 4 at the edges, while in the middle of the filter material strip 4 by the double laying of the strip on the tow-twist, the transmitted amount of light is reduced. In a spliced junction according to Fig. 2 takes because of the gaps between the fiber bundles the transmitted amount of light in the center too.

In Fig. 5 As an alternative example, a cross section through a reflection sensor arrangement 70 according to the invention is shown schematically, in which an optical sensor strip with a light strip 72 "is arranged on one side of a filter material strip 4. The light strip 72" can be integrated into the optical sensor strip 71 or in the conveying direction of the filter material strip 4 be arranged upstream or downstream. Optionally, laterally auxiliary light sources 72, 72 'can be arranged, which illuminate the surface of the filter material strip. The optical sensor strip 71 absorbs the amount of light reflected by the filter material strip 4. In the case of a tow-twist, the amount of reflected light at the edges of the strip of filter material 4 is reduced due to its sidecut, while in the center due to the duplication of the strip of filter material 4, the amount of light reflected is slightly increased. In the case of a ruptured weld as in Fig. 2 Also, waisting occurs, but the amount of reflected light in the center is reduced due to splitting.

Optionally, a mirror surface or reflective surface 73 may be arranged on the side of the filter material strip 4 opposite the optical sensor strip 71. The arrangement of the mirror surface serves to enhance the merits of the transmission process and the reflection process, i. of the transmitted light method and the incident light method, to connect with each other.

Fig. 6 shows a schematic side view of an acoustic sensor assembly according to the invention, wherein the filter material strip 4 is guided with a connection point 51 in the conveying direction shown with an arrow between the metallic surface of a drum 80 and a counter drum 81 therethrough. The thickened Point 51, when passing, excites the drum 80 to an acoustic vibration, which is picked up by an acoustic sensor 82. This sensor arrangement 80, 82 is particularly suitable for the thickened joints. The drums 80, 81, the downstream arranged drum pair 9 of a stretching device 3, 11 from Fig. 1 be.

In the Fig. 7 schematically illustrated sensor assembly includes an acceleration sensor 90 having a guide surface 91 for the filter material strip 4 and a pivot arm 92 which is deflected under the force exerted by the filter material strip 4 force. When a joint 51 is conveyed past the acceleration sensor 90, due to its greater density, it exerts an increased force over the guide surface 91, so that the rotation arm 92 is deflected. The acceleration occurring during the deflection is measured by the acceleration sensor 90. This sensor arrangement is particularly suitable for the detection of joints, less for tow-twists. In the 6 and 7 Sensor arrangements shown can thus serve, inter alia, in conjunction with an optical sensor for the discrimination of tow-twists and joints.

LIST OF REFERENCE NUMBERS

1

treatment device

2

processing device

2a

casing

3

roller pair

3a

control line

4, 4 '

Filter material strips

4a

Filter material strand

5

idler pulley

6, 6 '

bale

7

air nozzle

8th

air nozzle

9

roller pair

10

climatic chamber

10a

Steam source

10b

Warm air source

10c

control valve

10d

control valve

10e

control line

10f

control line

11

roller pair

12

applicator

13

Vorreckwalzenpaar

14

control

15

dancer roll

16

actuator

17

feed hopper

18

reel

19

gluing device

21

wrapping strip

22

format tape

22a

driving device

23

format

24

filter rod

25

main control

25a, b, c

control line

26

cooling fins

27

knife apparatus

28

filter rod

29

accelerator

31

offshoot drum

32

offshoot band

33

metering

33a

control line

34

feed

36

plasticizers stock

37

first measuring device

37a

reading

38

second measuring device

38a, b

reading

39, 39 ', 39 "

sensor

39a, b

signal line

42

evaluation

43

Control or regulating device

44

data line

45

junction

46

optical sensor

46a

reading

47

detection direction

48

connecting device

48 '

third sensor

49

guide ring

50 - 50 ^VII

Bundles of filter material

51 - 51 ^VII

join

52

conveying direction

53 - 53 "

Bottom edge of the filter material strip

54 - 54 "

Upper edge of the filter material strip

55

Constriction of the filter material strip

56

longitudinal axis

60

Transmission sensor arrangement

61

optical sensor strip

62

Strip-shaped light source

70

Reflective sensor arrangement

71

optical sensor strip

72

Auxiliary light source

73

mirror surface

80

Drum with metallic coat

81

against drum

82

acoustic sensor

90

accelerometer

91

guide surface

92

rotating arm

Claims (14)

1. Method of operating a filter rod machine (1, 2) in the tobacco processing industry, whereby filter material in the form of a filter material strip (4, 4') is drawn from a supply in the form of at least one bale (6, 6'), spread out, stretched, conveyed by an applicator unit (12) and fed to a formatting device (23) of the filter rod machine (1, 2), and a filter rod (24) is formed from the filter material strip (4, 4'), characterised in that at least one sensor (39; 39'; 60, 70, 80, 90) detects a defect (45, 51 - 51^VII; 55) after stretching the filter material strip (4, 4') and upstream of the applicator unit (12) and generates at least one signal (39a, 39b), which is used to ensure that at least the region of the filter rod (24) incorporating the defect (45, 51 - 51^VII; 55) is excluded from further processing.
2. Method as claimed in claim 1, characterised in that the defect (45, 51 - 51^VII; 55) is detected as being a change in the shape of the filter material strip (4, 4') caused by a joining point (45, 51 - 51^VII) in the filter material strip (4, 4') at which the end of the filter material strip (4, 4') of a first bale (6) is joined to the start of the filter material strip (4, 4') of a second bale (6') or caused by a 180° twist (55) of the filter material strip (4, 4') about its longitudinal axis (56).
3. Method as claimed in claim 1 or 2, characterised in that the defect (45, 51 - 51^VII; 55) is detected by means of an acoustic signal which is generated when the defect (45, 51 - 51^VII; 55) is conveyed alongside a drum (80) with a metallic surface.
4. Method as claimed in one of claims 1 to 3, characterised in that the defect (45, 51 - 51^VII; 55) is detected by means of an acceleration sensor (90).
5. Method as claimed in one of claims 1 to 4, characterised in that the defect (45, 51 - 51^VII; 55) is detected by means of an optical transmitted light and/or reflected light method, and the quantity of transmitted and/or reflected light is detected along at least a part of the width of the filter material strip (4, 4').
6. Method as claimed in claim 5, characterised in that at least one edge and in particular a region of the middle of the filter material strip (4, 4') is detected.
7. Method as claimed in one of claims 1 to 6, characterised in that the signal (39a, 39b) is used to reduce the conveying speed of the filter material strip (4, 4').
8. Filter rod machine (1, 2) in the tobacco processing industry with a filter material dispensing station from which a filter material strip (4, 4') can be dispensed from at least one filter material supply (6, 6'), with a spreading device (7, 8), a stretching device (3, 9), an applicator unit (12) and a rod formatting device (23) by means of which a filter rod (24) can be produced from the filter material strip (4, 4'), and at least one sensor (39, 39'; 60, 70, 80, 90) is provided which is designed to detect a defect (45, 51 - 51^VII; 55) of the filter material strip (4, 4'), and the sensor (39, 39'; 60, 70, 80, 90) is disposed at the point of or downstream of the stretching device (3, 9) and upstream of the applicator device (12), characterised in that an evaluation unit (25; 42, 43) is provided as a means of evaluating a signal of the sensor (39, 39'; 60, 70, 80, 90) for the presence of a defect (45, 51 - 51^VII; 55) of the filter material strip (4, 4').
9. Filter rod machine (1, 2) as claimed in claim 8, characterised in that a control unit (25) is provided, which in particular is integrated in the evaluation unit (25; 42, 43), by means of which, in particular by means of a timer or a shift register which is pre-settable and/or dependent on the conveying speed of the filter material strip (4, 4'), an ejection of filter rod portions or filter rods (28) affected by a detected defect (45, 51 - 51^VII; 55) and/or a reduction in the conveying speed of the filter material strip (4, 4') can be controlled.
10. Filter rod machine (1, 2) as claimed in claim 8 or 9, characterised in that the sensor (39, 39'; 60, 70, 80, 90) comprises a drum (80) with a metallic surface across which the filter material strip (4, 4') is fed, and the drum (80) is connected to an acoustic pick-up (82).
11. Filter rod machine (1, 2) as claimed in one of claims 8 to 10, characterised in that the sensor (39, 39'; 60, 70, 80, 90) is provided in the form of an acceleration sensor (90), in particular a lever (91, 92), across which the filter material strip (4, 4') is fed.
12. Filter rod machine (1, 2) as claimed in one of claims 8 to 11, characterised in that the sensor (39, 39'; 60, 70, 80, 90) comprises a light-sensitive sensor (61, 71) which is directed towards a surface of the filter material strip (4, 4') and disposed at a distance apart from the filter material strip (4, 4').
13. Filter rod machine (1, 2) as claimed in claim 12, characterised in that the sensor (61, 71) comprises a light-sensitive receiver element which is oriented in particular at an angle of approximately 90° with respect to the conveying direction of the filter material strip (4, 4').
14. Filter rod machine (1, 2) as claimed in claim 12 or 13, characterised in that a light source (62), in particular a row of light guides, is provided, disposed on the side of the filter material strip (4, 4') lying opposite the sensor (61), or a light source (72, 72', 72"), in particular a row of light guides (72) is provided, disposed on the same side of the filter material strip (4, 4') as the sensor (37), in which case a reflector (73) in particular is disposed on the side of the filter material strip (4, 4') lying opposite the sensor (37).

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