QUALITY TESTING OF ROD-SHAPED PRODUCTS OF THE TOBACCO PROCESSING INDUSTRY

Description

[0001] The invention relates to a method for measuring at least one quality parameter of rod-shaped products from the tobacco processing industry, in particular heat-not-burn products, wherein the rod-shaped products are conveyed transversely to their longitudinal axis. The invention further relates to a measuring device for the tobacco processing industry, comprising a conveying device for conveying rod-shaped products from the tobacco processing industry, in particular heat-not-burn products, wherein the conveying device has receiving troughs for receiving the rod-shaped products, wherein the conveying device is designed to convey the rod-shaped products in a direction transverse to the longitudinal axis of the receiving troughs.

[0002] In the tobacco processing industry, it is important to examine the quality of manufactured rod-shaped products, such as filter cigarettes, filter rods, multi-segment filter rods, and heat-not-burn products, in order to exclude rod-shaped products that do not meet quality requirements from further production or, preferably, to influence the production machine through control or regulation technology in such a way that the quality parameters are maintained during operation or the quality of these rod-shaped products is improved. Several prior art documents are known in this regard, such as WO 2015 / 138440 A1 or DE 10 2014 213 244 A1. Both of these patent applications show measuring devices by means of which rod-shaped products from the tobacco processing industry can be examined with regard to their properties.

[0003] DE 10 2014 209 721 A1 describes a method for determining a property of a rod-shaped article in the tobacco processing industry. The rod-shaped article is placed on a rotatable sample holder and irradiated with X-rays.

[0004] DE 10 2015 112 441 A1 discloses an X-ray testing device and a foreign matter detection method. For this purpose, a sample, which is moved in a specific direction, is illuminated with X-rays, which are detected by a TDI sensor.

[0005] For the purposes of this patent application or patent, a quality parameter is understood to include a diameter, roundness, the position of segments, the shape of segments, the inner diameter of a tube, the presence and / or location of additional elements, such as liquid-filled capsules, the length of the rod-shaped product, and similar parameters. There are, in particular, products for which conventional measurement methods fail because they use materials that are unsuitable for conventional measurement methods. In particular, heat-not-burn products have an aluminum foil wrapped around the rod-shaped products or are provided as the outermost layer or one of the outer layers of such rod-shaped products. These products do not allow for a transmission image in the optical or infrared range.The use of X-rays per se is also hardly suitable for such products, since the rapid conveyance of such products in machines in the tobacco processing industry means that sufficient contrast in the transmission images cannot be expected even when X-rays are used.

[0006] The object of the present invention is to enable a reliable and highly accurate measurement of quality parameters even in rod-shaped products of the tobacco processing industry which have components that make a conventional transmission measurement difficult.

[0007] This object is achieved by a method for measuring at least one quality parameter, in particular the length of one or more segments or a type of at least one segment, of rod-shaped products of the tobacco processing industry, in particular heat-not-burn products, wherein the rod-shaped products are conveyed transversely to their longitudinal axis and during conveyance X-rays pass through the rod-shaped products, wherein the transmitted X-rays are recorded by means of an area detector and a transmission image of the respective rod-shaped product is generated by means of a time delay integration.

[0008] The method according to the invention and the resulting longer exposure time result in significantly higher contrast and thus higher image quality. The evaluation of the transmission image, particularly by means of digital image processing, is thus simplified and has greater accuracy. In particular, it is preferred if the time delay integration is or is synchronized with the conveying speed of the rod-shaped products. In this case, a speed signal is preferably provided to a control device that controls the recording of the transmission image by the area detector, so that the time delay integration is preferably synchronized depending on the conveying speed of the rod-shaped products.

[0009] Preferably, the transmission image of the respective rod-shaped product is integrated synchronously with the conveying movement of the rod-shaped product. This enables very precise transmission images and also significantly increases the contrast.

[0010] Furthermore, very precise images with minimal blur are possible if the rod-shaped products are completely positioned in a receiving trough of a conveyor device during the measurement. Preferably, the rod-shaped products are suctioned into the receiving trough during the measurement to fix them in place.

[0011] Preferably, at least a portion of the receiving recess is radiation-permeable to the X-rays. Within the scope of the invention, radiation-permeable means an absorption of less than 50%, particularly preferably less than 40%, particularly preferably less than 30%, particularly preferably less than 20%, particularly preferably less than 10%. It can also preferably be provided that at least a portion of the receiving recess provides no absorption of the X-rays, for example, if a recess or a slot is provided in the receiving recess through which the X-rays can pass, specifically directly into the rod-shaped product.

[0012] Preferably, the conveying device has at least one section, transverse to the longitudinal axis of the rod-shaped products or the receiving trough, adjacent to the receiving trough, that is substantially opaque or completely opaque to X-rays. In this region, which is substantially opaque or completely opaque to X-rays and is adjacent to the receiving troughs, a material is preferably used that has a high absorption coefficient for the X-rays used, and / or a sufficient thickness of the material is provided.

[0013] According to one embodiment of the method, a transmission image of the rod-shaped product is formed in that, as the X-ray radiation passing through the rod-shaped product passes over the area detector, different lines or groups of lines of the area detector are taken into account one after the other for the integration of the signal, synchronized with the speed of the conveyance of the rod-shaped products in the conveying direction. In the event that the X-ray radiation falling next to the receiving troughs or the rod-shaped products contributes little or not to the transmission image, the image is very precise for the entire time that the image of the rod-shaped product falls on the area detector. In the event that interfering radiation is emitted by adjacent areas of the receiving trough orSince the respective rod-shaped product also falls on the area detector, preferably only an area that represents the transmission image of the rod-shaped product at a certain point in time should contribute to the integration. The background radiation can be eliminated by measuring the intensity outside the area where the image of the rod-shaped product falls on the area detector and subtracting it. This can be achieved with appropriate control and image processing.

[0014] Alternatively, time-delay integration can be performed in such a way that the exact location of the image of the rod-shaped product on the area detector is determined at any given time, for example, by detecting the contour of the image. Only those pixels within the image can then be considered for integration. A pixel matrix is ​​assigned to the image, so to speak, with the respective pixels moving relative to the location of the image as the image moves.

[0015] Preferably, the rod-shaped product is measured over its entire length. Particularly preferably, the rod-shaped product is measured over its entire diameter.

[0016] In addition, image processing can take into account the fact that the edge areas of the recording wells may contribute somewhat more to X-ray absorption, since there is slightly more material there in the direction of the X-ray beam. This can be taken into account during image processing.

[0017] The basic principle of time-delay integration is described in EP 2 088 763 A2. A suitable area detector can be a CCD image sensor, for example, the CCD 5061 from BAE Systems Imaging Solutions. This is a CCD sensor with 6,144 pixels by 128 lines. This can be read out at 80 MHz with a line rate of up to 12 kHz.

[0018] Instead of a CCD as an area detector, line CCDs arranged in an array or an array of line detectors can also be used.

[0019] With a sampling frequency of, for example, 10 KHz, sampling between 50 µm and 500 µm can be achieved depending on the size of the pixels and the size of the rod-shaped products to be measured and the conveying speed.

[0020] The object is further achieved by a measuring device of the tobacco processing industry comprising a conveyor device for conveying rod-shaped products of the tobacco processing industry, in particular heat-not-burn products, wherein the conveyor device has receiving troughs for receiving the rod-shaped products, wherein the conveyor device is designed to convey the rod-shaped products in a direction that is transverse to the longitudinal axis of the receiving troughs, wherein an X-ray source is provided and an area detector is provided that is arranged such that the area detector detects the X-ray radiation passing through a receiving trough and a rod-shaped product received in the receiving trough, wherein a control device is provided that is designed to generate a transmission image of the rod-shaped product by means of time-delay integration when the rod-shaped product is conveyed.

[0021] Preferably, the area detector has an extension in the conveying direction that is greater than the diameter of the rod-shaped product or greater than the diameter of the receiving trough.

[0022] Preferably, the rows of pixels or lines of the area detector are perpendicular to the conveying direction or parallel to the longitudinal axes of the receiving troughs.

[0023] In particular, the extension of the area detector in the conveying direction is preferably between two and five times the diameter of the rod-shaped product or the diameter of the receiving trough.

[0024] The complete rod-shaped product can preferably be measured if the extension of the area detector transverse to the conveying direction corresponds at least to the length of the rod-shaped product or the length of the receiving trough.

[0025] Preferably, the receiving troughs are at least partially X-ray transparent in an area intended for receiving the rod-shaped products. Preferably, the entire receiving trough is X-ray transparent.

[0026] In the context of the invention, X-ray-permeable means that the thickness of the material and / or the material selection is such that less than 50%, in particular less than 40%, in particular less than 30%, in particular less than 20%, in particular less than 10% of the X-ray radiation is absorbed by the material upon passing through the receiving recess. Preferably, the receiving recess is provided with a slot in sections so that no X-ray absorption occurs there at all. The receiving recess is thus free of material in the region of the slot.

[0027] Preferably, the material thickness of the receiving trough is less than or equal to 1 mm, at least in sections. Particularly preferably, the material of the receiving trough is aluminum, at least in sections, or comprises aluminum. To ensure appropriate stability of the conveying device, an annular surround is preferably provided on the end face of the receiving troughs to stabilize the receiving troughs.

[0028] The use of X-rays is proposed for measuring quality parameters of rod-shaped products in the tobacco processing industry, especially heat-not-burn products. Since heat-not-burn products are often completely wrapped in aluminum foil, conventional sensor methods cannot be applied or can only be applied to a limited extent. The quality parameters measured include, among others, the position of segments, the length of segments, the spacing between segments, and the material of the segments.

[0029] The products to be inspected are guided through an X-ray beam on a cross-axial conveyor device, such as a conveyor drum, a cantilever spider, or a conveyor belt. Line detectors with so-called time-delay integration (TDI) technology are particularly suitable for dynamic processes. In this case, the image is integrated, particularly analogically, synchronously with the linear object movement within the TDI sensor or area detector in the scanning direction. The resulting longer exposure time results in significantly higher image quality. In addition, evaluations are simplified and more accurate using digital image processing. Thin-walled conveyor elements, which only slightly attenuate the X-ray signal, are particularly preferred for the measuring method and device.

[0030] The invention makes it possible to precisely determine, even in complex products from the tobacco processing industry, whether the segments used are in the correct position, whether the correct segments are inserted, or even whether segments are missing, and whether these segments are the correct length. Furthermore, statements can be made about the correct positioning of inserted materials, such as threads, capsules, strips, and the like.

[0031] The X-rays are preferably generated using a standard X-ray tube with a suitable focus. The tube voltage of a commonly used X-ray tube should be between 5 keV and 450 keV. The X-ray beam is preferably collimated to the area to be examined or the X-ray beam is appropriately shaded to avoid or reduce parasitic scattering effects and thus artifacts in the imaging.

[0032] Depending on the material density, different materials experience different absorption and scattering effects of X-rays. The transmitted radiation is directed to a receiver. The receiver is preferably an area detector, preferably with a scintillation layer and can preferably be a CMOS or CCD. Furthermore, a line detector or area detector with TDI technology is preferably used. In this case, the image is integrated analogously synchronously with the linear object movement within the TDI sensor in the scanning direction. The resulting longer exposure time enables significantly higher image quality. The resulting high-resolution images can be very easily evaluated using digital image processing algorithms.

[0033] Due to the Lambert-Beer attenuation law I = I 0 e − μ ⋅ d (where I = intensity, I 0 = base intensity, µ = absorption coefficient and d = thickness) it is sensible not to include any additional highly absorbing materials, i.e. dense materials, in the beam path for the materials to be measured. For this reason it is sensible to use conveying devices that have little material in the area in which the rod-shaped products are held. For example, thin sheet metal troughs or thin receiving troughs are provided which, in the trough area, i.e. the support area for the rod-shaped product, only consist of a thin sheet metal with wall thicknesses of less than or equal to 1 mm. The material is preferably aluminium because aluminium is very permeable to X-rays. The thin wall thickness should preferably be applied over the entire length of the rod-shaped product.

[0034] To increase the rigidity of the conveying device, such as a conveyor drum, solid rings are provided on the front end, enclosing the walls of the receiving troughs. Furthermore, the control flange must be adjusted so that no material is in the beam path between the X-ray tube and the area detector. The walls of the receiving troughs can also be made of other materials such as plastic, composite materials, or other materials with low X-ray absorption. Instead of a conveyor drum, a conveyor belt can also be provided, which is conveyed via appropriate conveyor belt drums.

[0035] 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.

[0036] 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: Fig. 1 is a schematic sectional view of part of the measuring device according to the invention in a first embodiment, Fig. 2 is a schematic sectional view of part of a conveyor drum, Fig. 3 is a schematic view of a measuring device according to the invention in a further embodiment, Fig. 4 is a schematic plan view of a section of a conveyor drum.

[0037] In the drawings, identical or similar elements and / or parts are provided with the same reference numbers, so that a repeated presentation is omitted.

[0038] Fig. 1shows a schematic sectional view of part of a measuring device according to the invention. Receiving troughs 15 are provided on a conveyor drum 16, in which rod-shaped products 10 are held. The conveyor drum 16 is rotated or moved in the conveying direction 14.

[0039] X-ray radiation 12 is generated by an X-ray source 20 and sent toward the area detector 13. As the rod-shaped product 10 passes through the X-ray radiation 12, which is configured here in the form of a cone, the transmission image of the rod-shaped product is recorded by the area detector 13. During this process, the transmission image is moved during the movement of the rod-shaped product 10 in the conveying direction 14. Fig. 1The transmission image moves from right to left on the area detector 13. The transmission image is integrated accordingly, so that a very high-contrast transmission image is generated by means of time-delay integration. The areas between the receiving recesses 15 have a relatively thick wall, so that relatively little X-ray radiation passes through there. The material here can be stainless steel, for example, which absorbs the X-ray radiation well. The receiving recess 15 can be made of aluminum at least in sections or completely of aluminum and have a relatively thin wall, so that X-rays pass through here easily, in order to enable the best possible image of the material of the rod-shaped product 10.

[0040] Fig. 2shows a schematic sectional view of a section of a conveyor drum 16 in another embodiment. The receiving trough 15 has a portion made of a material and an otherwise material-free area 18 or a slot 18 to prevent any absorption of X-rays in this area by additional material that is not part of the rod-shaped product.

[0041] Fig. 3schematically shows another embodiment of a measuring device according to the invention. A conveyor belt 17 is deflected over two drums 25. The conveyor belt 17 is conveyed in the conveying direction 14. Receiving troughs 15, into which rod-shaped products 10 are inserted, are mounted on the conveyor belt 17. For clarity, only some of the receiving troughs 15 and the rod-shaped products 10 are shown. Between the two drums 25, an X-ray source 20 is provided, which emits X-ray radiation 12 in the direction of the area detector 13. Here, too, a precise image of the respective rod-shaped products 10 is enabled by time-delay integration.

[0042] In order to enable a synchronization of the time delay integration with the conveying speed of the rod-shaped products 10, a control device 21 is provided both in the embodiment according to Fig. 1 as well as in the embodiment according to Fig. 3provided, which controls the recording and reading of the area detector 13 via a control line 24. The control device 21 receives a speed signal from the machine control and processes this signal in such a way that, based on the geometric conditions, the speed signal is converted into a signal that represents the speed of the image of the rod-shaped product 10 on the area detector 13 in order to enable synchronized integration of the signal.

[0043] Fig. 4shows, in a further embodiment, a section of a conveyor drum 16. Three receiving troughs 15 are shown, wherein rod-shaped products 10 are introduced into two receiving troughs and one receiving trough has been left open in order to illustrate properties of this receiving trough 15. The receiving trough 15 is essentially thin-walled and has a slot 18 in the central region, i.e. an area in which no material is arranged. In order to ensure that the receiving trough is stable, particularly in the edge region, a border 23 is provided which is also connected to the material provided between the receiving troughs 15 of the conveyor drum 16. The rod-shaped products indicate several segments. Typically, however, an aluminum foil, for example, is wrapped around these segments, so that the various segments themselves would not be visible in a plan view.

[0044] Instead of the beam cone shown in the figures, parallel or essentially parallel X-ray beams can also be used.

[0045] Within the scope of the invention, features marked with "in particular" or "preferably" are to be understood as optional features.

[0046] All mentioned features, including those revealed solely in the drawings 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. List of reference symbols

[0047] 10rod-shaped product 11longitudinal axis 12X-ray radiation 13area detector 14conveying direction 15receiving trough 16conveyor drum 17conveyor belt 18slot 20X-ray source 21control device 22front side 23frame 24electrical connection control line 25drum

Claims

1. A method for measuring at least one quality parameter, in particular the length of one or more segments or a type of at least one segment, of rod-shaped products (10) of the tobacco processing industry, in particular of heat-not-burn products, wherein the rod-shaped products (10) are conveyed transversely to their longitudinal axis (11) and while they are being conveyed X-ray radiation (12) passes through the rod-shaped products (10), wherein the transmitted X-ray radiation (12) is received by means of a flat-panel detector (13) and a transmission image of the respective rod-shaped product (10) is produced by means of time delay integration.

2. The method according to Claim 1, characterized in that the time delay integration is or will be synchronized with the conveying speed of the rod-shaped products (10), wherein the transmission image of the respective rod-shaped product (10) in particular is or will be integrated synchronously with the conveying movement of the rod-shaped product (10).

3. The method according to Claim 1 or 2, characterized in that the rod-shaped products (10) are each completely arranged in a receiving trough (15) of a conveying device (16, 17) during the measurement.

4. The method according to Claim 3, characterized in that at least a portion of the receiving trough (15) is permeable to the X-ray radiation (12).

5. The method according to Claim 3 or 4, characterized in that the conveying device (16, 17) transverse to the longitudinal axis (11) of the rod-shaped products (10) or of the receiving trough (15), next to the receiving trough (15), has at least a portion which is substantially impermeable or completely impermeable to the X-rays.

6. The method according to any one of Claims 1 to 5, characterized in that the rod-shaped product (10) is measured over the entire length of the rod-shaped product (10).

7. The method according to any one of Claims 1 to 6, characterized in that the rod-shaped product (10) is measured over the entire diameter of the rod-shaped product (10).

8. A measuring device of the tobacco processing industry, comprising a conveying device (16, 17) for conveying rod-shaped products (10) of the tobacco processing industry, in particular heat-not-burn products, wherein the conveying device (16, 17) has receiving troughs (15) for receiving the rod-shaped products (10), wherein the conveying device (16, 17) is configured to convey the rod-shaped products (10) in a direction which is transverse to the longitudinal axis (11) of the receiving troughs (15), wherein an X-ray radiation source (20) is provided and a flat-panel detector (13) is provided, which is arranged such that the flat-panel detector (13) detects the X-ray radiation (12) passing through a receiving trough (15) and a rod-shaped product (10) received in the receiving trough (15), wherein a control device (21) is provided, which is adapted to produce a transmission image of the rod-shaped product (10) by means of time delay integration when the rod-shaped product (10) is conveyed.

9. The measuring device according to Claim 8, characterized in that the flat-panel detector (13) has an extent in the conveying direction (14), which is larger than the diameter of the rod-shaped product (10) or larger than the diameter of the receiving trough (15).

10. The measuring device according to Claim 9, characterized in that the extent of the flat-panel detector (13) in the conveying direction (14) is between two to five times the diameter of the rod-shaped product (10) or the diameter of the receiving trough (15).

11. The measuring device according to any one of Claims 8 to 10, characterized in that the extent of the flat-panel detector (13) transverse to the conveying direction (14) corresponds at least to the length of the rod-shaped product (10).

12. The measuring device according to any one of Claims 8 to 11, characterized in that the receiving troughs (15) in a region which is provided for receiving the rod-shaped products (10) are permeable to X-rays at least in sections.

13. The measuring device according to Claim 12, characterized in that the receiving troughs (15) are provided with a slot (18) at least in sections.

14. The measuring device according to any one of Claims 8 to 13, characterized in that the material thickness of the receiving trough (15) is less than or equal to 1 mm at least in sections.

15. The measuring device according to any one of Claims 8 to 14, characterized in that the material of the receiving trough (15) is aluminum at least in sections.

16. The measuring device according to Claim 14 or 15, characterized in that an annular border (23) for stabilizing the receiving trough (15) is provided on the end face (22) of the receiving trough (15).