WO2005003747A1

WO2005003747A1 - Microwave resonator, textile machine comprising a resonator of this type, and a dielectric for this resonator

Info

Publication number: WO2005003747A1
Application number: PCT/EP2004/051175
Authority: WO
Inventors: Michael Ueding; Otmar Kovacs; Wolfgang Göhler; Chokri Cherif
Original assignee: Rieter Ingolstadt Spinnereimaschinenbau Ag
Priority date: 2003-07-01
Filing date: 2004-06-21
Publication date: 2005-01-13
Also published as: DE112004001115D2; DE112004001115B4; CN1816739B; CN1816739A; DE10334144A1

Abstract

The invention relates to a microwave resonator for or on a textile machine for connecting to a measuring device serving to measure the weight and/or moisture of fibrous material (FB) continuously conveyed through the resonator space (31; 331; 431; 531). The aim of the invention is to design the resonator in order to improve the measuring accuracy. To this end, the invention provides different advantageous embodiments of at least one electrically non-conductive dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) for placement in the resonator space (31; 331; 431; 531).

Description

Microwave resonator, textile machine with such a resonator and dielectric for such a resonator

The invention relates to a microwave resonator for connection to a measuring device for measuring the mass and / or moisture of fiber material continuously conveyed through the resonator space, and to a textile machine with such a microwave resonator.

The measurement of fiber properties in the textile industry is an essential prerequisite for the production of high-quality textiles. For example, the measurement of sliver masses is indispensable, in particular for the purpose of compensating for unevenness in one or more slivers presented to a spinning preparation machine. Such a measurement is also desirable and even necessary for quality control of the stretched material at the machine exit. Measured values for the sliver mass (the terms sliver cross-section or sliver thickness are also common; the terms are to be regarded as equivalent in the context of this illustration) are used in addition to the above-mentioned quality control to shut down the machine if the specified mass or thickness limit values are exceeded or undershot and thus no high-quality product is received.

So far, mainly mechanically scanning sensors have been used to determine the sliver mass or thickness of the sliver or slivers. Capacitive measuring devices are also known. A new method for measuring the sliver mass, on the other hand, is the use of microwaves. Here, microwaves generated by a microwave generator, the frequencies of which are preferably changed within a certain range by a computer, are coupled into a resonator room of a microwave resonator, through which the measurement also takes place Fiber material is continuously passed through. In accordance with the fiber material, the tape mass and the tape moisture, a resonance signal occurs at a characteristic microwave frequency, which after decoupling to determine the tape mass and / or the tape moisture can be evaluated by a computer. Such a method for other purposes is described, for example, in EP 0468023 B1, the disclosure content of which is hereby explicitly included. The advantages of such a measuring method by means of microwaves lie in particular in the fact that high-precision, contactless scanning of the fiber material is possible. Mechanical impairments of the belt and measurement inaccuracies due to the inertia of mechanical measuring elements are excluded.

It has been found that there are various problems relating to the interaction between the resonator and the fiber material passed through it. Problems have arisen in particular in the choice of the material with which the fiber ribbon (s) come into contact or through which they are guided through the cavity resonator, which lead to measurement inaccuracies, measurement fluctuations and drifts.

It is an object of the present invention to improve the microwave resonator for measuring the thickness or mass and / or moisture of fiber material conveyed through it.

In a microwave resonator of the type mentioned at the outset, this object is achieved by the features of independent claims 1, 10, 11, 12, 13 and 14. Furthermore, this object is achieved by a textile machine with such a resonator. In a further aspect, this task is solved by a dielectric for such a resonator.

According to a first aspect of the invention, the resonator has at least one dielectric (ie an electrically non-conductive spatial unit) - in one part or in several parts - which is designed to be protected against the absorption of moisture. It has been found that the absorption of moisture and, in particular, water by the resonator elements, which shield the fiber material passed through from the other areas of the cavity, does not result in sufficiently stable measurement results. In particular, a drift of the resonance signals as a function of the water absorption has been observed on the part of the elements or dielectrics shielding them or guiding the fiber bath or baths. As a reason emphasized that, due to the large dielectric constant of water (ε = 80) compared to fiber material (ε = 2-3), the absorption of even the smallest amounts of moisture in the range of 0.05%, for example, can be up to 40 times greater (80/2) produce with measuring accuracy, that is in the range of 2%. However, measurement accuracy in the range of 0.1% is aimed for, for example, with regulating systems!

According to this finding, according to the first aspect of the invention, at least one dielectric is formed in the passage area of the fiber material in such a way that absorption of moisture is substantially completely prevented. Using such a configuration, it was possible to ensure that the resonance signals are precise and meaningful with regard to the tape mass or tape thickness and / or the moisture of the textile material even over a longer period of time.

It has proven to be particularly effective if the at least one dielectric is polished or ground at least in sections at points that come into contact with the fiber material. In this way it can be prevented that moisture from the fiber material, in particular micro cracks, is absorbed in the dielectric. No room humidity can penetrate to any appreciable extent. It is therefore preferred if the entire exposed area of the dielectric is polished or ground.

A preferred material that is polished or ground on its surface at least in sections is ceramic. It has been found that such a treatment reduces the absorption of moisture and thus leads to more precise and reliable measurement results.

Another material for the at least one dielectric is Makrolon ^®. This plastic polymer has been found to also be a suitable shield and guide member in the sense of the dielectric according to the invention, and in particular as a substantially water-resistant. Makrolon ^® also has the advantage that it is relatively inexpensive. However, Makrolon ^{® is} not resistant to abrasion to the desired extent, so coating with ceramics or the like is advisable (see below). In a further alternative, the at least one dielectric is made from a plastic alloy, which offers the required property of very low to nonexistent moisture absorption.

In a particularly preferred embodiment of the invention, at least two electrically non-conductive subunits are arranged in a sandwich-like manner with respect to one another and together form a dielectric according to the invention. On one side of this at least two-layer arrangement, the fiber material is guided in a touching manner. Such a sandwich arrangement has the advantage that the subunit facing away from the fiber material - and thus advantageously facing a closed resonator space area - can have, for example, favorable dielectric properties (for example essentially temperature-independent dielectric constant and dielectric loss factor in a temperature range of, for example, 10 ° C to 100 ° C and in gigahertz Frequency range), while the subunit facing the fiber material guarantees the inventive protection against moisture absorption. Accordingly, it is not necessary to search for a single material for the dielectric, which ideally should have optimal properties for all requirements.

In an advantageous embodiment in this regard, the partial unit facing away from the fiber material consists of plastic, on which a covering partial unit facing the fiber material is arranged. In an alternative, the subunit facing away from the fiber material is made of ceramic, on which a covering subunit is also arranged. In both cases, the covering unit is particularly preferably designed as a moisture-sealing layer, which is advantageously formed from a ceramic layer or a plastic layer. This layer can in turn be polished or ground. According to an advantageous embodiment, the main constituent is aluminum oxide (Al ₂ O ₃ ), the percentage of which can be above 95% and preferably above 98%. According to another preferred embodiment, silicon nitride is used as the main component and preferably S1 ₃ N4-Y2O ₃ . In the case of a plastic layer, this can be made from a polycarbonate.

The moisture-sealing layer can be in the form of a thin layer or plate-shaped, so that in the latter case the at least one dielectric can also be made of two can be formed sandwiched ceramic plates. According to the above, the subunit facing the fiber material can also be designed as a plate, consisting essentially of waterproof aluminum oxide or possibly also silicon nitride.

Even if no sandwich-like arrangement of at least two subunits is provided, the at least one dielectric can likewise essentially consist of aluminum oxide or silicon nitride.

According to the second aspect of the invention, the dielectric constant and / or the dielectric loss factor of at least one dielectric in the cavity resonator of a microwave sensor is essentially constant in the measuring range lying in the gigahertz range. If several such subunits are combined to form a dielectric, for example in the aforementioned sandwich-like structure, their common dielectric constant and / or their dielectric loss factor is essentially constant in the above sense. The frequency range mentioned in the gigahertz range from 1-10 GHz has proven to be suitable for measuring resonance signals on a fiber material. Since it makes sense to vary the frequency in a suitable frequency range for determining the resonance frequency, it is therefore advantageous that the dielectric properties do not essentially change over this frequency range and in particular in the bandwidth of the measuring range.

Furthermore, according to the third aspect of the invention, it has been shown that it is of the utmost importance that the at least one dielectric does not essentially deform under temperature fluctuations. In other words, the coefficient of thermal expansion of the material of the at least one dielectric is as low as possible. It has been shown that deformations also result in a resonance frequency detuning. The coefficient of linear expansion is advantageously less than 10 and preferably less than 5 in a temperature range from approximately 10 ° C. to 100 ° C.

According to the fourth aspect of the invention, at least one dielectric lies against a resonator wall, the thermal expansions of the two elements being essentially the same. With this configuration, the In case of thermal expansion suppress relative shear stresses due to the high interlaminar shear strength. In this case, materials for the electrically conductive resonator walls that have a relatively large thermal expansion, for example aluminum, can also be used.

According to the fifth aspect of the invention, the thickness of the at least one dielectric or the total thickness in the case of several interacting dielectrics in the region of the fiber material passage is selected such that the spatial resolution of the microwave resonance signal, which is also determined by the working frequency, is not worse than approx. 1-2 cm. In the case of a cavity resonator which is operated in the frequency range between approximately 2-3 GHz, the microwave field can be focused in the region of a spatial resolution in the order of magnitude of approximately 1 cm by means of one or more dielectrics with the stated thickness. If no such focusing were carried out, the spatial resolution would be significantly poorer due to the resonator properties (spatial dimensions, operating frequency).

The dielectric constant of the at least one dielectric is advantageously less than 20 and preferably less than 10 under conditions customary in machine operation, it also advantageously being essentially independent of temperature. Such a low dielectric constant is advantageous if, despite careful material selection, temperature fluctuations and frequency changes have an effect on the dielectric properties. In this case, a small dielectric constant causes only small deviations in the resonance signal, so that the resonance signals still have the required accuracy.

In a preferred embodiment of the invention, which has already been mentioned above, the at least one dielectric closes off parts of the resonator chamber, in particular to prevent dust or loose fibers from penetrating into these cavity regions and interfering with the measurements due to resonance shifts.

As also previously indicated, the at least one dielectric is furthermore preferably designed and arranged to passively guide the fiber material through the resonator space. According to what has been said above, at least part of the at least one dielectric is therefore designed as a guide element. In this way On the one hand, the rest of the resonator space can be protected from fiber fly and dust if the closure is appropriate, and on the other hand precise guidance of the fiber material through the resonator space can be achieved. Furthermore, by choosing the appropriate material (see above), the microwave field can be focused for the purpose of spatial resolution in the order of magnitude of approximately 1-2 cm.

The at least one dielectric is advantageously arranged along the transport path of the fiber material through the resonator. For example, the material covers a space between two edge sections of the resonator in the manner of a bridge or a bridge, which can range from the resonator inlet to the outlet.

In a special embodiment of the invention in this regard, the microwave resonator is essentially formed by hollow half cylinders arranged parallel and spaced apart from one another, between which the fiber material is transported in the transverse direction of the cylinder. The resonator walls are in this case formed by the bent half-shells delimiting the half-cylinders, while the mutually facing, preferably straight delimiting surfaces of the half-cylinders are each formed by dielectrics arranged parallel and spaced apart from one another, between which the fiber material is passed.

An embodiment in this regard is characterized in that the at least one dielectric is designed as a rectangular tube which is open on both end faces and has one or more pieces.

In particular, at the outlet of a drafting system, the resonator chamber can be designed as a flat hollow cylinder which is closed at the edges transversely to the fiber sliver transport direction (in contrast to the two previously mentioned half cylinders). In this embodiment, the fiber material is guided through the cylinder cavity in the direction of its longitudinal axis. Accordingly, the at least one dielectric also extends in the direction of the fiber material and is preferably designed as a one-piece or multi-piece cylinder tube that is open on both end faces. This can have an enlarged, advantageously conical inlet opening. In this case the fiber material can be used for a subsequent derwalzenpaar be compacted to a certain degree. This embodiment can be advantageous, for example, if only a single sliver is passed through the resonator, since here the round tube cross section can be adapted to the sliver cross section. However, the pipe cross section is advantageously cylindrical in shape over the geometric measuring range.

A resonator as described above can be used, for example, at the exit of a drafting system or at the inlet of a draw frame which receives a single strip from an upstream card.

Since the tube is preferably designed to be exchangeable, a suitable tube with a modified inner diameter can be selected, for example, depending on the fineness of the strip. The evaluation of the decoupled microwave signals is expediently matched to the tube used in each case. Such a readjustment of the evaluation software can be dispensed with if the masses of the various tubes in the area of the microwave propagation are chosen to be essentially the same size. This requires a suitable selection of the geometry of the pipes.

The above embodiment relates, inter alia, to the case where only one tube passes through the resonator chamber, ie the outside diameter of the respective tubes is the same with a different inside diameter. In alternative embodiments, at least two tubes are provided, an inner tube being arranged in a contactless or touching manner in an outer tube, for example pushed in. The fiber material is guided in the inner tube. In this case, different inner tubes with different inner diameters can also be used alternately in the preferably the same outer tube. The outer tube is used primarily to hold the inner tube and to keep the other resonator areas clean and is preferably arranged in a suitable manner on the resonator, for example suspended with an outer bead on the edge. In this embodiment, the accuracy of the resonance signal evaluation for the various inner tubes can also be ensured by readjusting the evaluation software and / or by equal massing of the inner tubes in the microwave propagation range. According to a sixth aspect of the invention, one or more dielectric materials, preferably made of ceramic, essentially fill the resonator space. On the outside, the dielectrics are surrounded by an electrically conductive layer or wall in order to allow the microwave field to arise in the interior. Since there is now ceramic or another suitable material in the resonator room instead of air, the spatial resolution can be increased or a very compact resonator can be built. According to an advantageous embodiment in this regard, the resonator comprises two semi-cylindrical dielectrics, between which the fiber material is passed.

Moreover, it should be noted that the dielectrics are preferred, at least on their side facing the fiber material, and are designed to be abrasion-resistant in accordance with an independent aspect of the invention, in order to counteract wear due to fiber friction. This is preferably achieved by a suitable choice of material, for example a ceramic with the main component aluminum oxide.

The invention relates, as it were, to a textile machine, in particular a card, draw frame or comber with at least one of the microwave resonators mentioned. The invention also includes the respective dielectrics for such microwave resonators. Otherwise, the microwave resonator according to the invention can also be used for other machines and apparatus or which do not originate from the textile sector.

Advantageous developments of the invention are characterized by the features of the subclaims.

The invention is explained in more detail below with reference to the figures. Show it:

1 shows a microwave resonator according to a first embodiment, cut along I-1 according to FIG. 2;

Figure 2a, 2b, 2c a tube for the microwave resonator in side view, in longitudinal section and in supervision; Figure 3 shows the microwave resonator of Figure 1 seen from above in a reduced view (fleece guide nozzle removed);

FIG. 4 shows a microwave resonator according to a second embodiment (same view as FIG. 1);

Figure 5 shows a microwave resonator according to a third embodiment in supervision;

FIG. 6 shows the microwave resonator according to FIG. 5 in a sectional side view (vertical section along the resonator along the transport direction of the fiber band FB);

Figure 6a shows a section of two sandwich-like dielectrics.

7 shows the microwave resonator according to FIGS. 5 and 6 in a rear view (section along I-1 in FIG. 5);

FIG. 8 shows a microwave resonator according to a fourth embodiment (same view as FIG. 5);

9 shows a microwave resonator according to a fifth embodiment in an exploded view, and

10 shows a microwave resonator according to a sixth embodiment.

1 and 3 show a first exemplary embodiment of a microwave resonator 30 in section and from above. The resonator 30 is arranged in a plate-shaped support structure 21. For this purpose, the support structure 21 has a central recess 32, which in the embodiment shown is cylindrical, as can be seen from the top view in FIG. 3. A wall element 46 is placed on the recess 32, which in the embodiment shown is designed as a flat cylindrical disk and has screw receptacles 36a on the edge, which are aligned with corresponding blind bores 36b in the support structure 21. As in the fi 3, hexagon screws 36 can be screwed into these bores 36a, 36b, each of which has an internal thread, in order to screw the wall element 46 to the support structure 21 (the screws are not shown in FIG. 1). In an alternative, not shown, the wall element 46 can be fitted and screwed plane-parallel in a recess in the support structure 21 with the upper side of the support structure 21.

The wall element 46 placed on the recess 32 creates a resonator chamber 31 of the microwave resonator 30, into which microwaves can be coupled in with the aid of a coupling element 58 and can be coupled out with the aid of a coupling element 59, see FIG. Figure 3. Both coupling elements 58, 59, for example in the form of a rod, project from the outside into the resonator space 31 through corresponding bores in the wall element 46. The coupling element 58 is connected via a cable 57 to a schematically indicated microwave generator 56, the frequency of which with the aid of a control unit (not shown) (preferably a microprocessor) can be varied. The decoupling element 59 is in turn connected via a cable 55 to an evaluation unit, not shown. The coupling-out element 59 receives the microwave signals which form in the resonator chamber 31 and forwards them to the evaluation unit, so that the respective resonance frequency and the associated signal width can be determined at successive times. From this information, the band mass or band thickness and the band moisture of the fiber material that is currently passing through the resonator chamber 31 can be determined.

A dielectric 60, which is essentially in the form of a hollow cylindrical guide tube and is made of an electrically non-conductive material, is inserted into the resonator chamber 31. The dielectric 60, which is shown in greater detail in FIGS. 2a-2c, has an outer bead on each end side, with which it bears in a through opening of the wall element 446 on the one hand and a through opening in the support structure 21 on the other. The fiber sliver FB, which is shown only schematically as an arrow, is guided linearly through the resonator chamber 31 and then through a sliver funnel 26 with a beak-shaped end section directly into the nip between two downstream calender rolls 11, 12. The band funnel 26 is in one Ring bead of the support structure 21 held and for this purpose has an annular groove.

The guide tube or the dielectric 60 is made of a material whose dielectric constant and its dielectric loss factor remain essentially constant in the measuring range lying in the gigahertz range. In addition, the dielectric constant and the dielectric loss factor remain essentially unchanged in the case of the temperature fluctuations customary in machine operation - typically between 20 ° C. and 70 ° C. The empty resonance frequency of the resonator 30 thus hardly changes from the point in time at which a band end emerges until the new introduction of fiber band, regardless of the time period in between, so that no new calibration of the microwave sensor has to be carried out.

The dielectric 60 in accordance with one aspect of the invention is designed such that it does not essentially deform under temperature fluctuations, i.e. has a low coefficient of thermal expansion. Furthermore, the material of the dielectric 60 is advantageously designed to be essentially resistant to abrasion.

According to a further aspect of the invention, the dielectric 60 is designed to be protected against the absorption of moisture. Various approaches are possible to achieve this goal. On the one hand, the inward-facing surface of the dielectric 60 can be ground or polished in order to prevent moisture absorption from the environment and from the fiber sliver FB via microcracks in the material. A ceramic with the main component aluminum oxide (Al ₂ O ₃ ) has proven to be a suitable material here.

If selected, an untreated, moisture-resistant material can also be used. Ceramics also consist essentially of aluminum oxide (Al2O ₃ ) _. that can be used without treatment. Silicon nitride ceramics may also be used, for example Si3N ₄ Υ2θ3.

It has been shown that aluminum oxide (Al ₂ O ₃ ) also has a high abrasion resistance and, moreover, a dielectric constant of less than 10 at the usual operating temperatures and at measuring frequencies in the range of approximately 1-10 GHz. Also their coefficient of linear expansion in a temperature range of approx. 20-100 ° C is below 10, in the case of Si ₃ N ₄ -Y ₂ θ ₃ even in the range of 3.

As can also be seen in FIG. 1, a fleece guide nozzle 23 is arranged above the wall element 46 and has a bore 70 into which a fleece nozzle insert 24 is inserted and held by means of a centering pin (not shown). On the side facing away from the dielectric or the guide tube 60, the fleece nozzle insert 24 is rounded on the circumference in order to ensure a gentle insertion of the fiber sliver FB into the guide tube 60. The fleece guide nozzle 23 is articulated on the support structure in such a way that it can be pivoted in the direction of the double arrow 27, in particular in the event of a tape jam on the nozzle 23. The articulation points of the fleece guide nozzle 23 on the narrow sides of the support structure 21 are not shown.

On the side of the wall element 46 facing away from the resonator 30, a first, electrical heating foil 80 is attached, while on the opposite side of the support structure 21 a second heating foil 85 is arranged on the outside. Both heating foils 80, 85 are connected to a heating source, not shown, via connecting wires 81, 82 or 86, 87. The heating power is advantageously regulated, for example to 70 ° C. for the outlet sensor shown (and approx. 35 ° C. for an inlet sensor). For this purpose, one or more temperature measuring devices (not shown) are expediently provided, which can be arranged, for example, in one or more lateral bores in the support structure 21 that come close to the resonator chamber 31. Thermal envelope insulation, which for example surrounds the entire support structure - with corresponding openings for the fiber material - can also be provided to prevent the influence of temperature fluctuations in the environment and to prevent loss of heating power.

Other additional or alternative measures for temperature stabilization can consist in that the the Resoπatorraum are made 31 surrounding elements of a material having low thermal expansion, for example, a steel with high nickel content, preferably Ni36 steel and in this case, for example Invar ^® steel. The inner wall of the cavity 30 may have a conductive coating of, for example, oxygen copper because of Invar ^® steel of the wall member 46 and the support structure 21 has a relatively low electrical conductivity. Microwave resonances with sufficient signal strength could possibly not develop without such a conductive coating. In order to prevent corrosion of the coating, a corrosion-resistant coating of, for example, gold or silver is additionally applied to it. Alternatively, a ceramic or a composite with embedded ceramic can be used as a coating or cover.

The resonator 30 with the dielectric 60 designed as a guide tube can advantageously be arranged behind a drafting system. The nonwoven fabric leaving the drafting system is formed into a band FB and then introduced into the resonator 30. In an alternative, the resonator 30 can be arranged between a card and a draw frame, the fiber material leaving the card being transported into a can in the drafting device of the draw frame without an intermediate storage.

FIG. 4 shows a further embodiment of a microwave resonator according to the invention, the only difference from that of FIGS. 1 and 3 is that two concentrically arranged tubes are provided as dielectrics 160, 161, an inner tube 160 and an outer tube 161 2a-2c is substantially the same as that according to FIGS. 2a-2c, the outer tube or the outer dielectric 161 is shorter and each has a step-shaped ring recess 163, 164 in the wall element 46 or in the support structure 21 stored. The outer dielectric 161 prevents penetration of dust and moisture into the eccentric areas of the resonator chamber 31 when the inner dielectric 160 is replaced, so that there is no need for a corrosion protection layer on the inner resonator walls. Such a replacement of the tube 160 is advantageous if inner dielectrics with different inner diameters are to be used, for example when the fiber material to be processed is changed. Advantageously, the total mass of the inner and outer dielectric 160, 161 in the area of the microwave propagation in the resonator chamber 31 is essentially constant, since in this case the empty resonance frequency remains unchanged and there is no need for new calibrations. The inner wall of the outer Tube 161 is preferably designed to be moisture-resistant, for example by polishing or grinding to remove microcracks and / or by applying a moisture-resistant layer (for example Al ₂ O ₃ ).

FIGS. 5-7 show a further microwave resonator 300 - shown without a microwave generator - with an upstream funnel 318 and calender rollers 335, 336, the pair of calender rollers pulling at least one fiber band FB through the funnel 318 and the resonator 300. In FIGS. 5 and 6, the at least one fiber sliver FB is only indicated by a dotted arrow; in FIG. 7 the fiber sliver FB is shown in cross section as a composite of many individual fibers. If a plurality of fiber slivers FB are transported through the resonator 300, these advantageously lie next to one another. 7, the hopper 318 and the calender rollers 335, 336 are not shown. In addition, the rollers 335, 336 can also serve as drafting rollers of a drafting system, so that they perform a double function (transport through resonator 300 and drafting).

Instead of a funnel 318, other band guide elements can also be used, for example horizontally and / or vertically arranged deflecting rods, which for example can also have concave guide surfaces in order to allow the at least one fiber band FB to enter the resonator 300 centered. Furthermore, the calender rolls 335, 336 can be arranged rotated by 90 ° or any other angle.

The resonator 300 has two closed hollow half cylinders 301, 305 separated by a gap 310, the outer walls 302, 306 of the half cylinders 301, 305 being made of metal. The inner walls oriented towards the fiber band FB are designed as dielectrics 303, 307 in the sense of this invention. The material for these plate-shaped dielectrics 303, 307 are made, for example, from a ceramic with the main constituent aluminum oxide or another suitable material, reference being made here to the above explanations regarding the guide tube 60. The microwave resonance forms in the resonator interior between the walls 302, 306. The thicknesses of the dielectrics 303, 307 are chosen so that the spatial resolution of the microwave resonance signal is not worse than approx. 1-2 cm. same for preferably also for the configuration of the dielectrics 60, 160, 161 of the embodiments according to FIGS. 1-4.

The plate-shaped dielectrics 303, 307 are preferably designed to be exchangeable and can easily be replaced if damaged, for example. For example, the dielectrics 303, 307 are glued to the edges of the resonator walls 302 and 306, but nevertheless are relatively easy to replace after the glue points have been cleaned.

The fiber material FB is passively guided along the rounded corners 309 of the resonator walls 303, 307 and further along the dielectrics 303, 307, see FIG. Figure 7. Since the respective interiors of the half cylinders 301, 305 are sealed off from the environment, advantageously no dust, fiber fly or the like can penetrate them. For the sake of clarity, the coupling-in element 358 and coupling-out element 359 protrude into these interiors.

In the sliver running direction, an air flow 350 can be passed through the gap 310 on both sides of the sliver FB or slivers FB, which is dashed in FIGS. 3 and 4 and shown in FIG. 5 as a circle with crossed lines drawn therein (air flow direction from the viewer ) directed away. The air flow or the air flows 350, of which several can also be distributed over the resonator width, can assume several functions. On the one hand, they ensure a largely homogeneous temperature distribution in the gap 310, on the other hand, they prevent deposits of fibers in particular on the dielectrics 303, 307 and at the exit of the resonator 300 or at the transition to the calender rollers 335, 336. Such dirt deposits would prevent this Detune resonator 300 and lead to measurement inaccuracies.

Furthermore, the air flow 350 can be used for the targeted temperature setting, in particular of the resonator walls 302, 306. In particular, it is possible to use cooling air in order to cool the resonator walls to a temperature that is as constant as possible in comparison to normal operation.

As with the dielectrics 60, 160, the dielectrics 303, 307 can be ground or polished, at least on their side facing the fiber material FB to prevent the ingress of moisture. The other above explanations regarding the choice of materials also apply accordingly.

Furthermore, it is advisable to construct the dielectrics 303, 307 from a plurality of sandwich-like layers or partial units, as is shown enlarged in FIG. 6a. The subunit 307a facing the respective hollow half cylinder 301, 305 can have optimal dielectric properties, for example an essentially constant dielectric constant and an essentially constant dielectric loss factor in the case of temperature fluctuations and in measurement frequency ranges in the gigahertz range. The subunit 307b facing the gap 310 can in particular be designed in such a way that moisture absorption and abrasion due to the fiber material passing through are substantially prevented. Accordingly, for example, for each hollow half-cylinder 301, 305 facing sub-unit 307a, a ceramic such as TMM ^® (a hydrocarbon-ceramic composite material with a very good temperature stability and in particular a to temperature variations very stable dielectric constant) or a plastic (for example, Makrolon ^®) or a plastic alloy can be selected, while for the partial unit 307b facing the gap 310 and which is either layered or plate-shaped, it consists of a ceramic made of aluminum oxide as the respective main component. This ceramic can in turn be ground or polished.

It should be noted that all of the embodiments of the dielectrics shown in the figures can be constructed in a sandwich-like manner from two or more layers.

The embodiment of the microwave resonator 400 according to FIG. 8 (sectional view as in FIG. 6 with the omission of upstream and downstream elements) differs from that according to FIGS. 5-7 in that the dielectrics 403, 407 extend over the entire transport length of the fiber material FB extend through the resonator 400 and are rounded at their input and output ends 409 to avoid an abrupt transition for the fiber material. In this embodiment, the resonator walls 402, 406 serve as a flat contact surface on which the dielectrics 403, 407 are preferably glued. The dielectrics 403, 407 can be designed like the dielectrics 303, 307 in terms of material and treatment. In the embodiment of the microwave resonator 500 according to FIG. 9, two resonator walls 502, 506 and a dielectric 503 according to the invention to be arranged between them, preferably made of ceramic, are shown in an exploded view. This resonator 500 also has two hollow half-cylinders 501, 505 spaced apart from one another in the thickness of the dielectric 503, which together with the dielectric 503 form the resonator space 531. The dielectric 503 lies on the circumferential edges of the respective walls 502, 506, which can be screwed to one another via schematically illustrated bores. The dielectric 503 preferably has rounded leading and trailing edges 509. Antenna connections are not shown in FIG. 9.

FIG. 10 shows one half of a further embodiment of a microwave resonator 600 according to the invention. This resonator has two semi-cylindrical dielectrics 603, 607 made of preferably ceramic, between which the fiber material FB is passed as in the case of the resonators in FIGS. 5-9. An electrically conductive layer, for example made of copper, is applied to the curved outside of the dielectrics 603, 607. In an alternative, rigid metal walls are provided instead of the layers. The layers or walls can be provided on the outside with a corrosion layer, for example a copper layer; This layer is not absolutely necessary, since the microwave field forms in the interior of the resonator 600. Antenna connections 608a, 608b for coupling in for coupling out microwaves are provided on an end face of the dielectrics 603, 607. On the side facing the fiber material, measures are preferably taken to prevent the penetration of moisture (grinding, polishing, coating, etc., see above).

By means of the resonator 600 comprising the two voluminous dielectrics 603, 607, each with an electrically conductive layer or wall on the outside, the microwave field (when using measuring frequencies in the GHz range) can be focused to a few millimeters in the measuring range of the fiber material passage. With such a resonator, the spatial resolution can be increased compared to that of FIGS. 5-9, since they contain air instead of the solid dielectrics. In addition, the resonator 600 can be made very compact due to the configuration according to the invention. The above statements regarding the other microwave resonators described apply to the type of material and any treatment of the surfaces of the dielectrics 603, 607. The dielectrics 603, 607 can accordingly each consist, for example, of a larger semi-cylindrical ceramic or plastic block with a temperature and frequency stable and as low as possible dielectric constant, which is provided with a moisture-resistant and essentially abrasion-resistant ceramic layer made of aluminum oxide.

In all of the previously discussed embodiments, there are contact surfaces between the dielectrics and the resonator walls, which preferably serve as adhesive surfaces at least in sections. For this purpose, an adhesive with low moisture absorption is preferably used. According to one aspect of the invention, the thermal expansions of the at least one dielectric and the at least one resonator wall are essentially of the same size, so that there are no relative shear stresses between the dielectric and the resonator wall which lead to cracks and leaks and thus to measurement errors.

It is of course also advantageous if the loss of loss of the at least one electrically non-conductive dielectric according to the invention is as low as possible in accordance with the various aspects of the invention, that is to say the dielectric comes as close as possible to an ideal non-conductor.

The described microwave resonators with a microwave generator can be used, for example, on a line with a regulated or unregulated drafting system. In the case of a regulated drafting system, a microwave sensor can be arranged before and after the drafting system. The invention can also be used, for example, without restriction in a carding machine or a comber.

Claims

Patent claims

1. Microwave resonator for or on a textile machine, in particular a card, draw frame or comber, for connection to a measuring device for measuring the mass and / or the moisture of fiber material (FB) conveyed continuously through the resonator chamber (31; 331; 431; 531) , characterized in that at least in the area of the passage of the fiber material (FB) through the resonator (30; 300; 400; 500; 600) at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603 , 607) is arranged or can be arranged, which is designed to be protected against the absorption of moisture.

2. Microwave resonator according to claim 1, characterized in that at least a portion of the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607), which comes into contact with the fiber material (FB) , polished or polished to prevent the absorption of moisture.

3. Microwave resonator according to claim 2, characterized in that the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) with the polished or ground section consists of ceramic.

4. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) is made of Makrolon ^® .

5. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) is made of a plastic alloy.

6. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) from at least two electrically non-conductive, sandwich-like sub-units (307a , 307b), the fiber material (FB) being guided with contact along one of the at least two subunits (307a, 307b).

7. Microwave resonator according to claim 6, characterized in that the sandwich-like dielectric (307) comprises a subunit (307a) made of plastic and a subunit (307b) arranged thereon and facing the fiber material (FB).

8. Microwave resonator according to claim 6 or 7, characterized in that the sandwich-like dielectric (307) comprises a partial unit (307a) made of ceramic and a covering unit (307b) arranged thereon and facing the fiber material (FB).

9. Microwave resonator according to claim 8, characterized in that the covering unit (307b) is designed as a sealing layer, preferably as a ceramic layer and here preferably essentially made of aluminum oxide or silicon nitride, or as a plastic layer, for example made of polycarbonate.

10. Microwave resonator for or on a textile machine, in particular a card, draw frame or comber, in particular according to one of the preceding claims, for connection to a measuring device for measuring the mass and / or the moisture continuously through the resonator chamber (31; 331; 431; 531) conveyed fiber material (FB), characterized in that at least in the region of the passage of the fiber material (FB) through the resonator (30; 300; 400; 500; 600) at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) is arranged or can be arranged, the dielectric constant and / or dielectric loss factor of which remains essentially constant in the measuring range lying in the gigahertz range.

11. Microwave resonator for or on a textile machine, in particular a card, draw frame or comber, in particular according to one of the preceding claims, for connection to a measuring device for measuring the mass and / or the moisture continuously through the resonator chamber (31; 331; 431; 531) conveyed fiber material (FB), characterized in that at least in the region of the passage of the fiber material (FB) through the resonator (30; 300; 400; 500; 600) at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) is arranged or can be arranged, which essentially does not deform when the temperature fluctuates (low coefficient of thermal expansion).

12. Microwave resonator for or on a textile machine, in particular a card, draw frame or comber, in particular according to one of the preceding claims, for connection to a measuring device for measuring the mass and / or the moisture continuously through the resonator chamber (31; 331; 431; 531) conveyed fiber material (FB), characterized in that at least in the region of the passage of the fiber material (FB) through the resonator (30; 300; 400; 500; 600) at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) is arranged or can be arranged, which abuts at least one resonator wall (21, 46; 302, 306; 402, 406; 502, 506), the thermal expansions of the at least one dielectric (60; 160 , 161; 303, 307; 403, 407; 503; 603, 607) and the at least one resonator wall (21, 46; 302, 306; 402, 406; 502, 506) are essentially the same size.

13. Microwave resonator for or on a textile machine, in particular a card, draw frame or comber, in particular according to one of the preceding claims, for connection to a measuring device for measuring the mass and / or the moisture from continuously through the resonator chamber (31; 331; 431; 531) conveyed fiber material (FB), characterized in that at least in the region of the passage of the fiber material (FB) through the resonator (30; 300; 400; 500; 600) at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) is arranged or can be arranged, the total thickness of the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) being selected such that the spatial resolution the microwave resonance signal is not worse than approx. 1 - 2 cm.

14. Microwave resonator for or on a textile machine, in particular a card, draw frame or comber, in particular according to one of the preceding claims, for connecting to a measuring device for measuring the mass and / or the moisture of fiber material (FB) continuously conveyed through the resonator chamber by at least one solid dielectric (603, 607), which essentially fills the resonator space and which of a electrically conductive layer or wall is surrounded, the microwave field being formed in the resonator space enclosed by the layer or wall.

15. Microwave resonator according to claim 14, characterized in that the resonator (600) comprises two semi-cylindrical dielectrics (603, 607), between which the fiber material (FB) is passed.

16. Microwave resonator according to one of the preceding claims, characterized in that the dielectric constant of the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) under the conditions customary in machine operation is less than 20 and advantageously in is essentially independent of temperature.

17. Microwave resonator according to one of the preceding claims, characterized in that the dielectric constant of the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) is less than 10 and under the conditions customary in machine operation is advantageously essentially independent of temperature.

18. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503) seals cavity areas of the resonator (30; 300; 400; 500).

19. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) for passively guiding the fiber material (FB) through the Resonator space (31; 331; 431; 531) is formed and arranged.

20. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (60; 160, 161; 303, 307; 403, 407; 503; 603, 607) extends essentially from the resonator inlet to the resonator outlet.

21. Microwave resonator according to one of the preceding claims, characterized in that it is essentially formed by two hollow, parallel and spaced-apart half-cylinders (301, 305) between which the fiber material (FB) can be transported in one or more fiber strands in the transverse direction of the cylinder is, the half cylinders (301, 305) on their mutually facing sides being closed by means of said dielectrics (303, 307; 403, 407).

22. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (303, 307; 403, 407) is plate-shaped and is arranged along the transport path of the fiber material through the resonator space (331; 431).

23. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (503) is designed as a rectangular tube that is open on both end faces and has one or more pieces.

24. Microwave resonator according to one of the preceding claims, characterized in that it essentially comprises an edge-side closed, cylindrical-shaped resonator chamber (31), in which the at least one dielectric (60; 160, 161) can be inserted running in the direction of its longitudinal axis.

25. Microwave resonator according to one of the preceding claims, characterized in that the at least one dielectric (60; 160, 161) is designed as a one-piece or multi-piece cylinder tube which is open on both end faces.

26. Microwave resonator according to one of the preceding claims, characterized in that different tubes (60; 160) which can alternatively be used in the resonator chamber (31) are provided, each having essentially the same outside diameter and different inside diameter.

27. Microwave resonator according to one of the preceding claims, characterized in that at least two are used simultaneously in the resonator chamber (31). bare tubes (160, 161) are provided, an outer tube (161) surrounding an inner tube (160).

28. Microwave resonator according to one of the preceding claims, characterized in that different tubes (60) or tube combinations (160, 161) which can alternatively be used in the resonator space (31) have essentially the same total mass in the range of the microwave propagation.

29. Textile machine, in particular card, draw frame or comber, characterized by at least one microwave resonator (30; 300; 400; 500; 600) according to one of the preceding claims.

30 dielectric (60; 16, 161; 303, 307; 403, 407; 503; 603, 607) for a microwave resonator (30; 300; 400; 500; 600) according to one of the preceding claims.