Suction belt conveyor and rod-forming machine of the tobacco processing industry, and use and method for measuring material properties of a material rod of the tobacco processing industry

Abstract

Suction belt conveyor of a rod-forming machine of the tobacco processing industry for conveying materials, in particular tobacco, a rod-forming machine of the tobacco processing industry and use of the rod-forming machine and a method for measuring material properties of a material rod of the tobacco processing industry. The suction belt conveyor includes at least one rod guiding channel, which is open at the bottom and which is delimited by two lateral channel sides and a suction belt along a conveying path. At least one electromagnetic measuring device is integrated in the channel sides of the suction belt conveyor at at least one position along the conveying path in order to determine properties of the conveyed material.

Claims

1. A suction belt conveyor for conveying material, comprising: at least one rod guiding channel, which is open at a bottom and is delimited by two lateral channel sides and a suction belt along a conveying path; and at least one electromagnetic measuring device integrated in at least one of the lateral channel sides at least one position along the conveying path to determine properties of the material being conveyed, wherein the at least one electromagnetic measuring device comprises a microwave measuring device with at least one resonator cavity, and wherein the suction belt conveyor is configured for conveying tobacco in a rod-forming machine of the tobacco processing industry.

2. The suction belt conveyor according to claim 1, wherein the microwave measuring device comprises at least one measuring opening oriented toward the conveying path.

3. The suction belt conveyor according to claim 1, wherein the microwave measuring device comprises two coaxial resonators recessed in the two channel sides opposite each other.

4. The suction belt conveyor according to claim 1, wherein the at least one resonator cavity has a rectangular cross-section in each of the two lateral channel sides, each of the rectangular cross-sections being arranged flush with a respective one of the two lateral channel sides at least one rod guiding channel.

5. The suction belt conveyor according to claim 1, wherein the microwave measuring device comprises a reverse U-shaped slotted rectangular resonator that encloses three sides of the at least one rod guiding channel.

6. The suction belt conveyor according to claim 5, wherein the slotted rectangular resonator comprises three antennas, of which two antennas are arranged symmetrically to the lateral channel sides of the at least one rod guiding channel, and a third antenna is arranged in a plane of symmetry of the at least one resonator cavity above the at least one rod guiding channel.

7. The suction belt conveyor according to claim 6, wherein one of: the two symmetrically arranged antennas are excited in-phase, and the third antenna serves as a decoupling antenna, or the third antenna is excited, and the two symmetrically arranged antennas serve as decoupling antennas.

8. The suction belt conveyor according to claim 1, further comprising at least one microwave-absorbing body recessed in at least one of the lateral channel sides at least one of upstream and downstream, with respect to a suction belt conveying direction, from the at least one resonator cavity.

9. The suction belt conveyor according to claim 1, wherein at least one of power and measuring electronics are arranged on the suction belt conveyor.

10. A rod-forming machine comprising the suction belt conveyor according to claim 1.

11. The rod-forming machine according to claim 10 being positionable in a tobacco rod-forming machine of the tobacco processing industry.

12. A method of operating an electromagnetic measuring device in the suction belt conveyor according to claim 1, wherein the electromagnetic measuring device comprises the microwave measuring device with the at least one resonator cavity, and the suction belt conveyor is arranged in the rod-forming machine in the tobacco industry, the method comprising: holding tobacco material sprinkled from below onto the suction belt with suction air; and measuring material properties of the held tobacco material.

13. A method for measuring material properties of a material rod, comprising: sprinkling material for the rod onto the suction belt of the suction belt conveyor according to claim 1 from below; conveying the material via the suction belt along the conveying path through the at least one rod guiding channel of the suction belt conveyor; and measuring, in the at least one rod guiding channel and along the conveying path, material properties of the conveyed material on the suction belt with the at least one electromagnetic measuring device of the suction belt conveyor.

14. The method according to claim 13, wherein the material rod is a tobacco rod of the tobacco processing industry.

15. The method according to claim 13, wherein the microwave measuring device operates with a resonant method.

16. The method according to claim 15, wherein the resonant method is performed as a transmission method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below, without restricting the general idea of the invention, based on exemplary embodiments in reference to the drawings, wherein we expressly refer to the drawings with regard to the disclosure of all details according to the invention that are not explained in greater detail in the text. In the following:

(2) FIG. 1 shows a schematic overview of a cigarette rod-forming machine;

(3) FIGS. 2A and 2B schematically show a perspective detail drawing and a cross-sectional view, respectively, of a rod guiding channel provided in the known cigarette rod-forming machine of FIG. 1;

(4) FIGS. 3A-3C show a schematic representation of a first embodiment of a suction belt conveyor with a microwave measuring device having a field distribution and emission characteristic;

(5) FIGS. 4A-4C show a schematic representation of another embodiment of a suction belt conveyor with a microwave measuring device, field characteristic and emission characteristic;

(6) FIGS. 5A-5C show another alternative embodiment in a schematic representation of a suction belt conveyor with a microwave measuring device, field characteristic and emission characteristic;

(7) FIGS. 6A-6E show a schematic representation of another alternative embodiment of a suction belt conveyor with a slotted rectangular conveyor with detail drawings, a field distribution and emission characteristic;

(8) FIGS. 7A-7C show schematic representations of the actuation of a corresponding slotted rectangular resonator with emission characteristics;

(9) FIGS. 8A and 8B show schematic representations of absorption elements for the channel sides of a suction belt conveyor according to the invention; and

(10) FIG. 9 shows a schematic representation of an embodiment of a suction belt conveyor with a capacitive measuring device with a field distribution.

(11) In the drawings, the same or similar types of elements and/or parts are provided with the same reference numbers so that a re-introduction is omitted.

DETAILED DESCRIPTION

(12) The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.

(13) FIG. 1 schematically portrays a known cigarette rod-forming machine according to DE 10 2011 082 625 A1, the design and operation of which will be explained below.

(14) A predistributor 2 is loaded in portions with tobacco fibers (not shown in the figures) from a sluice 1. A takeout roller 3 in the predistributor 2 supplies a tank 4 with tobacco fibers from the predistributor 2. A steep-angle conveyor 5 removes the tobacco fibers from the tank 4 and feeds a bulking chute 6. From the bulking chute 6, a pin roller 7 removes a substantially uniform stream of tobacco fibers, which is beaten out of the pins of the pin roller 7 by a picker roller 8, and flung onto an apron 9 that circulates at a constant speed. A tobacco carpet forms on the apron 9 from the stream of tobacco. The tobacco carpet is flung into a sieving device 11 which substantially consists of an air curtain that lets larger or respectively, heavy tobacco parts pass by, whereas all other tobacco particles are dropped by the air into a funnel 14 formed by a pin roller 12 and a wall 13.

(15) The tobacco fibers are conveyed out of the funnel 14 by the pin roller 12 to the suction belt conveyor 160 in a rod guiding channel 16 and are flung there against a lower run, forming the floor of the rod guiding channel 16, of an air-permeable continuously circulating suction belt 17 with a vacuum applied to the rear, onto which a rod-shaped tobacco fiber cake consisting of the tobacco fibers is sprinkled that is accordingly held on the lower run of the suction belt 17 with the assistance of air drawn into a vacuum chamber 18. Via the circulating suction belt 17, the tobacco fiber cake sprinkled, or respectively collected therein is conveyed as a suspended rod along the rod guiding channel 16. The bottom run of this suction belt 17 extends through the rod guiding channel 16 from its beginning where the rod-forming zone is located, in the depicted exemplary embodiment up to an equalizer or trimmer 19 to remove excess tobacco fibers.

(16) Then the tobacco fiber rod formed in this manner is placed on a strip of cigarette paper 21 running in sync. The strip of cigarette paper 21 is drawn by a bobbin 22, guided through a print unit 23, and placed on a driven garniture tape 24. The garniture tape 24 transports the tobacco rod together with the strip of cigarette paper 21 through a format 26 in which the strip of cigarette paper 21 is folded around the tobacco rod so that only a narrow edge stands up which is glued in a known manner by a glue mechanism (not shown). Then the adhesive seam formed in this manner is closed and dried by a tandem seam sealer 27.

(17) The cigarette rod 28 formed in this manner passes through a measuring unit 29 and is cut by a knife mechanism 31 into double-length cigarettes 32. The double-length cigarettes 32 are transferred by a transfer apparatus 34 having controlled arms into a take-over drum 36 of a filter assembler 37, on whose cutting drum 38 they are divided into individual cigarettes using a circular knife.

(18) Conveyor belts 39, 41 convey excess tobacco fibers trimmed by the trimmer 19 into a container 42 disposed beneath the tank 4, from which the excess tobacco fibers are removed as returned tobacco by the steep-angle conveyor 5.

(19) FIGS. 2A and 2B show an assembly or unit that includes the known rod guiding channel 16 from DE 10 2011 082 625 A1.

(20) The assembly, which includes the rod guiding channel 16, has a frame 46 through which this assembly is arranged in the machine depicted in FIG. 1. The rod guiding channel 16 is open at the bottom and has two lateral sides 16a, 16b at a distance from each other. Moreover, FIG. 2B shows a schematic cross-section of the bottom run 17a of continuously circulating suction belt 17 (see FIG. 1), which forms the floor (lying at the top) of the rod guiding channel 16. The cavity 16c and hence also the cross-section of the rod guiding channel 16 is delimited by the two side channel sides 16a, 16b and the bottom run 17a for of the suction belt 17. The distance between the two side channel sides 16a, 16b of the rod guiding channel 16 determines the width of the rod-shaped tobacco cake sprinkled in the cavity 16c of the rod guiding channel 16.

(21) In the depicted example, at least one of the two lateral sides 16a, 16b can be adjusted transversely to the rod conveying direction identified by arrow X in FIG. 2A, i.e., lateral side 16a and/or 16b can be adjusted in the direction of double arrow Y in FIGS. 2A, 2B. Given the adjustability of at least one of the two lateral sides 16a, 16b, their distance from each other and hence the clearance width of the cavity 16c of the rod guiding channel 16 can be changed, which also brings about a corresponding change in the width of the rod-shaped tobacco cake sprinkled in the cavity 16c of the rod guiding channel 16. With the given cross-sectional area of the rod-shaped tobacco cake sprinkled in the cavity 16c of the rod guiding channel 16, changing the width also has an influence on the deposited height.

(22) The lateral sides 16a, 16b are adjusted using a drive device 48 that is actuated by a subsequent regulation in which the distance between the two channel sides 16a, 16b, or respectively the clearance width of the cavity 16c of the rod guiding channel 16, forms the manipulated variable.

(23) The measuring unit 29 above is preferably designed to detect the cross-section, the ovality, or respectively roundness and/or the density of the cigarette rod 28, and/or the weight of the cigarettes 32, and/or the weight of the cigarette rod 28 per unit length, and/or the degree to which the cigarette rod 28 is and/or the cigarettes 32 are filled with fiber, and is designed to emit a corresponding output signal A. The output signal A is transmitted to a controller 50. As FIG. 1 schematically reveals, a distance sensor 52 is provided on the rod guiding channel 16 that detects the deposited height of the rod-shaped tobacco cake in the rod guiding channel 16 and transmits a corresponding output signal B to the controller 50. The distance sensor 52 is arranged upstream from the trimmer 19.

(24) Another distance sensor 56 is provided on the rod guiding channel 16 with the assistance of which the respective actual value for the clearance distance between the two lateral sides 16a, 16b of the rod guiding channel 16, and accordingly the width of its cavity 16c, are detected, and a corresponding signal F is transmitted to the adjusting device 54. The controller 50 processes a target value signal C as another input variable, by which a corresponding target value is specified for the parameter(s) to be controlled. These three signals A, B and C are processed in the controller 50 that, as a result, produces an output signal D in order to correspondingly actuate a downstream adjusting device 54.

(25) FIGS. 3A and 3B schematically show a section of a first exemplary embodiment according to the invention of a suction belt conveyor with coaxial resonators 206, 207 recessed in the channel sides 102, 104. These can be, but do not have to be, designed like the channel sides 16a, 16b from FIGS. 2A and 2B. Preferably, the channel sides are designed solid outside of the microwave measuring devices.

(26) A section of a rod guiding channel 100 is shown, in which the rod conveying direction 108, or the conveying path 108, is indicated with an arrow. Between the channel sides 102, 104, a suction belt 106 extends that is moved in the rod-conveying direction 108 and is sprinkled with material up to a fill height 112, which is also a till depth since sprinkling is from below. A cover 110 is arranged above the suction belt 106 and limits the emissions at the top from a microwave measuring field from the coaxial resonators 206, 207. In the schematic depiction, the rear channel side 102 is depicted solid, and the front channel side 104 is depicted semi-transparent. The cover 110 is actually a single piece and does not consist of two halves as depicted, merely for the sake of clarity, in the schematic representation in FIG. 3A.

(27) The coaxial resonators 206, 207 of the microwave measuring device 200 each have a resonator cavity 202, 203 as can be easily seen in FIG. 3B. A coaxial antenna 208, 209 is centrally arranged in each resonator cavity 202, 203. The resonator cavities 202, 203 open toward the guide channel 100 with openings 204, 205 so that an electromagnetic microwave field indicated with arrows penetrates the guide channel 100.

(28) A coordinate system is shown both in FIG. 3A and FIG. 3B in which the Z direction corresponds with the conveying path 108, the X direction, which is perpendicular to the Z axis, is in a horizontal direction, and the Y direction, which is perpendicular to the Z axis, is in a vertical direction. Both coaxial resonators 206, 207 are preferably λ/4 coaxial resonators short-circuited at the end. The greatest field strength occurs at the interface of the open end of the respective coaxial resonator 206, 207 and attenuates toward the center of the guide channel 100. The coaxial resonators 206, 207 have an emission characteristic maxima that are particularly pronounced in the Z and X direction, as shown in FIG. 3C.

(29) FIGS. 4A and 4B schematically portray an alternative exemplary embodiment according to the invention. In contrast to the microwave measuring device 200 from FIG. 3, the microwave measuring device 220 in FIGS. 4A and 4B is a symmetrical assembly with two resonator cavities 222, 223 that have a rectangular cross-section, each of which opens to the guide channel 100 with an opening 224, 225. The extension of the resonator cavities 222, 223 in the direction of the conveying path 108 is much larger than transverse thereto so that an electrical field with primarily a Y component (E.sub.y) is formed. The corresponding antennas 228, 229 penetrate the resonator cavities 222, 223 in a vertical direction from below to generate the microwave field with a dominant Y component.

(30) The field strength distribution of the E.sub.y field component is portrayed in FIG. 4B. The penetration of the guide channel 100 is evidently effective. The vertical dimension of the resonator cavities 222, 223 is much less than one-half wavelength of the wavelength of the used microwave measuring field of between 4 and 6 GHz. The dimension in the rod direction is greater than one-half wavelength so that a mode, its field component in the Y direction, can propagate vertically relative to the rod direction 108 (Z direction).

(31) The short distance of the cover 110 to the suction belt 106 is also easily discernible in FIG. 4B. As the distance of the cover 110 to the suction belt 106 increases, the resonance frequencies of the different modes that are excited approach each other, which has advantages in terms of measurement. At the same time, however, undesirable emissions increase, so that a smaller cover distance is desirable for the emissions. An exemplary field distribution and emission characteristic in the guide channel is depicted in FIG. 4C.

(32) FIGS. 5A and 5B schematically portray another exemplary embodiment of a suction belt conveyor according to the invention with a microwave measuring device 240. As shown in a perspective view in FIG. 5A, there are two rectangular resonators 246, 247 recessed in the channel sides 102, 104 with rectangular resonator cavities 242, 243 which, like in the previous exemplary embodiments, are flush with each other and penetrate the guide channel 100 at the level of the material sprinkled onto the suction belt 106. The rectangular resonator cavities 242, 243 have a short extension of less than one-half wavelength of the microwave measuring field in the rod direction 108, and more than one-half wavelength transverse thereto in a vertical (Y) direction.

(33) As can be seen in FIG. 5B, the antennas 248, 249 with their antenna cables 248a, 249a are arranged symmetrically on both sides and extend in the rod direction 108, i.e., the Z direction, into the resonator cavities 242, 243. A field with electrical field lines is excited in the Z direction (E) as the main component. At the locations of the openings 244, 245 in the guide channel 100, this penetrates the material in the guide channel 100 and attenuates toward the center. Overall, the electrical field effectively penetrates the material, and the measuring window in the Z direction is narrower than with the E.sub.y resonator in FIGS. 4A-4C. However, the X component of the electrical field propagates into the channel side and, as can be seen in the emission characteristic in FIG. 5C, produces scattered radiation in the Z direction.

(34) FIGS. 6A-6D schematically portrays another exemplary embodiment with a microwave measuring device 260 with a slotted rectangular resonator 266 that extends in a reverse U-shape around the guide channel 100, or respectively the material, below the suction belt 106 and is open at the bottom to allow an exchange of the suction belt. In the center, slotted openings 265 are discernible in FIG. 6A, which define a very narrow measuring window in the Z direction. A perspective view of a cross-section of the resonator cavity 262 of the slotted rectangular resonator 266 is schematically portrayed in FIG. 6B. Toward the center, i.e., toward the guide channel 100 with the material, the cross-section of the resonator cavity 262 narrows in the Z direction via a collar 272. The couplings 268a, 269a of two antennas 268, 269 are depicted that extend in the Z direction into the resonator cavity 262. The microwave field in the resonator forms within the entire U-shaped resonator.

(35) FIG. 6C shows a cross-section in the Y-Z plane through the guide channel 100 and the slotted rectangular resonator 266 in which the embodiment of the collar 272 is easily discernible as well as the arrangement of the antenna 269 extending into the resonator cavity 266 in the Z direction, and the arrangement of the antenna cable 269 outside thereof.

(36) FIG. 6D shows the field distribution of the electrical field strength in a front view with the cross-sectional plane in the center of the slot 265 for the resonator 266 according to FIG. 6A-6C. In the shown structure, the electrical field decreases downward and toward the middle but, however, has the advantage that it directly borders the material, and there are no construction-related distances with the exception of windows transparent to microwaves that prevent the resonator cavity 262 from becoming soiled. The sensor has the greatest sensitivity of all microwave measuring devices described up to this point.

(37) The emissions shown in FIG. 6E are the greatest in the Z direction and, in comparison to the other exemplary embodiments, have a maximum emission.

(38) Different configurations of the actuation of the slotted rectangular resonator 266 are shown in FIG. 7A-7C.

(39) With a symmetrical resonator such as the slotted rectangular resonator 266, two propagatable modes are excited: the “common” mode in which the electrical field lines (E) in the rod run (primarily) parallel thereto and the magnetic field (H) encloses both antennas 268, 269; and the “differential” mode in which the electrical field lines run (primarily) orthogonally to the rod between the antennas 268, 269. The actual field distribution is ultimately an overlap of the two modes. Common, or respectively differential mode can be excited separate from each other when the coupling and decoupling antenna (coupling element) are excited in common mode (FIG. 7A), or respectively differential mode (FIG. 7B). It was revealed that differential mode is the mode that excites so-called plate modes in the channel side that can propagate and radiate there as shown in FIG. 7B.

(40) FIG. 7C shows an exemplary embodiment according to the invention in which the insight about in-phase excitation is advantageously implemented to reduce emissions.

(41) According to the depicted exemplary embodiment, the two symmetrically arranged antennas 268, 269 are excited in-phase (for example, by a single signal division with a Wilkinson divider), and effectively represent an electrode (coupling or decoupling). The other electrode 270 is inserted into the plane of symmetry as depicted in FIG. 7C. Given this arrangement, no field distributions are excited that possess horizontal field components perpendicular to the rod. In this way, an emission of the microwave output into the surroundings can be advantageously at least partially suppressed.

(42) An arrangement without the second electrode in the plane of symmetry is also conceivable. In this case, the resonator is operated with reflection.

(43) The dimensions of the slotted rectangular resonator 266 move within a range of about 50 to 100 mm in the Z direction, about 50 to 100 mm in the Y direction, and about 70 mm in the X direction. Other dimensions are of course also possible and realizable according to the invention.

(44) One way to reduce emissions, in particular by plate modes in the channel sides, is schematically portrayed in FIGS. 8A and 8B, which show schematic sectional representations of the guide channel 100 with channel sides 102, 104 in which are recessed elements 300, 302 that absorb opposite from each other and include a material with a complex dielectric constant such as a microwave-absorbing rubber material, foam, etc. These draw power from the emitted microwave field to reduce the emissions to the outside. FIG. 8B shows the arrangement of such absorbing elements 300, 302, 304, 306 upstream and downstream from the slotted rectangular resonator 266 in the channel sides 102, 104. The corresponding absorbing elements 300 to 306 are, for example, to be inserted in cavities in the channel sides 102, 104 created therefor along the direction of propagation. The achieved damping increases with the size and the layer thickness of the absorbing material. In the case of two side-by-side 3×3 centimeter layers, a basic mode of the TEM plate mode can be dampened by more than 10 dB in the direction of propagation.

(45) FIG. 9 shows a plan view of a suction belt conveyor according to the invention with a rod guiding channel 100 which is delimited by the channel sides 16a, 16b and a capacitive measuring device 320.

(46) The capacitive measuring device comprises two cutouts (cavities) 321, 322 that are provided opposite each other in the channel sides 16a, 16b and are filled with air or a dielectric. An electrode 323, 324 is inserted in each cutout. As can be seen in FIG. 9, the structure of the capacitive measuring device is similar to that of a plate capacitor.

(47) The effective measuring window is determined by the field lines which are depicted by arrows in FIG. 9. The field lines also determine the actual effective measuring capacity. The remaining field lines are ascribable to stray capacitances.

(48) All named features, including those taken from the drawings alone and individual features, which are disclosed in combination with other features, are considered alone and in combination as essential for the invention. Embodiments according to the invention can be fulfilled through individual features or a combination of several features. In the context of the invention, features which are designated with “in particular” or “preferably” are to be understood as optional features.

(49) It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

REFERENCE LIST

(50) 1 sluice 2 predistributor 3 take-out roller 4 tank 5 steep-angle conveyor 6 bulking chute 7 pin roller 8 picker roller 9 apron 11 sieving device 12 pin roller 13 wall 14 funnel 16 rod guiding channel 16a channel side 16b channel side 16c cavity and cross-section of the rod guiding channel 17 suction belt 17a bottom run 18 vacuum chamber 19 trimmer 21 strip of cigarette paper 22 bobbin 23 print unit 24 garniture tape 26 format 27 tandem seam sealer 28 cigarette rod 29 Measuring unit 31 knife mechanism 32 double-length cigarettes 34 transfer apparatus 36 take-over drum 37 filter assembler 38 cutting drum 39 conveyor belt 41 conveyor belt 42 container 46 frame 48 drive device 50 controller 52 distance sensor 54 adjusting device 56 distance sensor 100 rod guiding channel 102 channel side 104 channel side 106 suction belt 108 conveying path 110 cover 112 fill height 160 suction belt conveyor 200 microwave measuring device 202, 203 resonator cavity 204, 205 opening 206, 207 coaxial resonator 208, 209 coaxial antenna 220 microwave measuring device 222, 223 resonator cavity 224, 225 opening 226, 227 rectangular resonator 228, 229 antenna 240 microwave measuring device 242, 243 resonator cavity 244, 245 opening 246, 247 rectangular resonator 248, 249 antenna 248a, 249a antenna cable 260 microwave measuring device 262 resonator cavity 264, 265 opening 266 slotted rectangular resonator 268, 269 antenna 268a, 269a antenna cable 270 antenna 272 collar 300, 302 absorbing element 304, 306 absorbing element 320 capacitive measuring device 321, 322 cutouts 323, 324 electrodes