Measuring arrangement for determining ultrasonic measurement data

Abstract

Measuring arrangement for determining ultrasonic measurement data from the interior of a tubular body, in particular ultrasonic measurement data of a material moving in the tubular body, wherein the measuring arrangement (100) comprises a tubular body (2) with an outer casing and at least one ultrasonic sensor or ultrasonic transmitter (1) for emitting ultrasonic waves into the interior of the tubular body (2), wherein the ultrasonic sensor (1) is arranged in and / or on the outer casing of the tubular body (2) at a coupling angle α of 1° < α ≤ 89°, measured between the longitudinal axis of the ultrasonic sensor (1) and a straight line running normal to the longitudinal axis of the tubular body (2).

Description

The invention relates to a measuring arrangement for ascertaining ultrasonic measurement data from the interior of a tubular body according to patent claim 1.Conveyors with a conveying element, for example a conveying screw, which rotates inside a tubular body, and single-screw extruders and multi-screw extruders for processing and melting polymeric materials are sufficiently known in a variety of configurations.Likewise sufficiently known are devices comprising a combination of a container, cutter compressor or a preconditioning unit (PCU) and an extruder connected thereto for pretreatment and processing of polymer waste, in particular of different thermoplastic materials. Such combination devices have long been known, for example from EP 2 558 263 or EP 2 689 908.All sealing threads supported in a worm housing and--although to a lesser extent--their housings are subject to wear, even in the case of best armouring. In addition, in particular in the case of those screws which convey a material mixed with abrasive constituents, for example, predominantly thermoplastic, plastic material from the recycling industry which is more or less contaminated, deposits occur both on the screw base and on the screw housing, in addition to the wear. In the case of screws which feed against an extruder head, the wear or deposits mentioned have the consequence that the feed action required for a satisfactory extrusion of the material can no longer be reliably built up in front of the extruder head, since the material slips back in an uncontrollable manner in the circumferential gaps between the screw and the housing, which gaps are caused by the wear and the deposits.The effects mentioned are particularly unpleasant in the case of sealing threads which are arranged in the manner described at the beginning. A loss of the conveying effect due to wear or deposition in the region of the sealing thread, which can occur both in a creeping manner and also abruptly in special cases, is noticeable by contamination of the material supplied to the further processing, so that the end product, as a rule granules obtained at the extruder head, is also contaminated. This leads to discounts of the final processors of the granulate. Contaminated granulate not only loses value, but the granulate production of weeks may have to be subjected to a second thermal filter process, which in turn entails the disadvantage that the second required heat treatment unnecessarily waste energy and the molecular chains of the plastic material are damaged.In order to avoid these difficulties, the sealing threads must be removed at regular intervals and both the housing and the worm must be checked for wear. However, these works are seldom carried out because they are time-consuming and have to be carried out by professionals, since the wear in the region of the sealing worm can occur both on the latter itself, namely not only with respect to the outer diameter of the screw threads, but also with respect to the core diameter of the sealing elements, and on the cylindrical worm housing. In addition, the wear does not always occur continuously and thus planable, but also abruptly and briefly in the case of correspondingly contaminated material.In the screw seal, material is prevented from entering the region between the screw and the gear. This sealing action separates the melt / dust and the atmosphere, and material arcing is prevented. Under certain circumstances, it may happen that the seal is insufficient and melt is forced through the seal in the opposite direction. This can lead to problems, e.g. wear, deposits, unfavourable pressure conditions, loss of conveying action, high moisture input, cracking, etc.It is also known to obtain information about the material moved therein by means of the introduction of ultrasound into the interior of pipes or the like. This is currently only inadequate, however, and with low accuracy.It is therefore an object of the present invention to provide a simple and reliable measuring arrangement for the online determination of high-quality ultrasonic measurement data from the interior of a tubular body or material.The invention achieves this object with a measuring arrangement for introducing ultrasound and for ascertaining ultrasonic measurement data from the interior of a tubular body, in particular ultrasonic measurement data of a material moving in the tubular body, according to patent claim 1.According to the invention, it is provided that the measuring arrangement comprises a tubular body with an outer jacket and at least one ultrasonic sensor or ultrasonic transmitter for emitting ultrasonic waves into the interior of the tubular body, wherein the ultrasonic sensor is arranged in and / or on the outer jacket of the tubular body at an incoupling angle α of 1°<α≤89°, measured between the longitudinal axis of the ultrasonic sensor and a straight line running normal to the longitudinal axis of the tubular body.In the context of the invention, a "tubular body" is understood to mean any elongated hollow body, in the interior of which material can move, irrespective of its outer or inner cross-sectional shape. Such a tubular body can have, for example, a circular, elliptical, rectangular or even a square cross-sectional area, and / or one or more bores for, for example, an extruder or a conveying element. In the present case, typical conveyors, extruders or pipelines, in particular with cylindrical interior spaces, are particularly suitable as "tubular bodies", wherein their external configuration is not relevant.An "ultrasonic sensor" is understood in the present case to mean a unit which is designed and suitable for emitting ultrasonic waves into the interior of the tubular body, for example an ultrasonic transmitter. The ultrasonic sensor can also be designed and suitable for detecting ultrasonic waves or for receiving reflected ultrasonic waves from the interior of the tubular body. The ultrasonic sensor can accordingly be a unit which, in addition to the emission of ultrasonic waves, is also designed at the same time for the detection of ultrasonic waves.The arrangement according to the invention of the ultrasonic sensor at an incoupling angle α of 1°<α≤89° advantageously ensures that the first reflection of the ultrasonic waves on the opposite inner wall of the tubular body is absent or at least is significantly weaker. This reflection on the inner wall of the tubular body is very strong at an angle of 90°, and the received reflected ultrasonic signal can only be amplified as much as the input voltage range allows, so that the first reflection would exceed all other reflections. If this first reflection is omitted or at least attenuated, this restriction is omitted and the ultrasonic sensor signal becomes better, since it can be amplified significantly higher.Furthermore, by avoiding or attenuating the first reflection, an ultrasonic sensor with higher power can advantageously be used and, by means of the oblique coupling, a larger region can additionally be scanned and changes in the wear and flow directions of the moved material in the interior of the tubular body can thus be identified more accurately, for example.With a measuring arrangement according to the invention it is thus possible on-line during operation of a conveyor or extruder, for example, to assist the monitoring of parameters of both the material moving or conveyed in the tubular body and of the tubular body or any conveying elements, sealing threads or the like arranged in the tubular body and in this way to obtain information about, for example, the degree of wear and / or the conveying effect of a tube or screw section conveying, for example a plasticized material, in particular plastic.It is likewise advantageously possible, for example in the case of sealing elements, to identify at any time whether an adequate conveying effect is present, which can be made possible, for example, by measuring the wear of the screw or, if appropriate, also of its screw housing, by measuring the free conveying cross section, i.e. measuring the free channel width and the free channel height, and also the conveying direction (flow vector), and this can also be made possible during ongoing production.With a measuring arrangement according to the invention or with a method described below, a wide variety of ultrasonic measurements can advantageously be realized, which provide information about the material transported in the interior of the tubular body, but also about the tubular body itself or about components such as screws in the tubular body. For example, geometric or material-induced effects can be examined. By measuring the flow direction, it is possible, for example, to obtain conclusions as to whether the flow takes place from the clean side to the dirty side. If the velocity vector becomes smaller or if it rotates completely (flow reversal is detected), this can be recognized and treated as a fault. Measurement or detection of gas bubbles and / or particles in the polymer melt is also possible. Particles or gas bubbles in the melt can be detected and measured in melt-carrying extruder zones. Both the direction of the particle flow or gas bubble flow can be detected and the basic presence of bubbles or particles can be detected.Further advantageous embodiment variants of a measuring arrangement according to the invention for ascertaining ultrasonic measurement data from the interior of a tubular body are described in the dependent claims.A particularly good attenuation of the first reflection of the ultrasonic waves on the inner wall of the tubular body can be achieved if the ultrasonic sensor is arranged in / or on the outer jacket of the tubular body at an incoupling angle α of 2° to 70° (2°≤α≤70°), in particular at an incoupling angle α of 6° to 25° (6°≤α≤25°).According to one embodiment variant of a measuring arrangement according to the invention, which ensures a further improvement of the signal of the ultrasonic sensor, it can be provided that the distance of the ultrasonic sensor from an irradiation surface and / or projection surface at the transition of the outer jacket of the tubular body to the interior of the tubular body, which is dependent on the incoupling angle α and the ultrasonic frequency, is greater than the near field length of the ultrasonic sensor, in particular greater than 10 mm, preferably 17 mm. Within the near zone or near field length, the ultrasonic field is non-linear, the intensity can fluctuate and displays can be mapped incorrectly in their amplitude or can be suppressed completely, so that it is advantageous to measure outside this range.According to a particularly advantageous embodiment variant of a measuring arrangement according to the invention, it can be provided that the distance Ds, measured from the center of the ultrasonic sensor normal to its irradiation surface and / or projection surface, which has a length, in particular a main axis length, at the transition of the outer jacket of the tubular body to the interior of the tubular body, is given by: wherein the divergence angle θ is given by the formula:where k=0.56 is an experimental constant, λ is the ultrasonic wavelength, and D is the width and / or diameter of the ultrasonic sensor.Such a configuration of a measuring arrangement according to the invention is particularly suitable for extruders of all types or sizes.A further improved adaptation of a measuring arrangement according to the invention to a wide variety of extruder types can be achieved if the ratio b / Ds of the length, in particular of the main axis length, b of the irradiation surface and / or projection surface to the distance Ds of the ultrasonic sensor is in a range from 0.001 to 1, in particular from 0.01 to 0.95, preferably from 0.016 to 0.9.According to one embodiment variant of a measuring arrangement according to the invention, which ensures a further improvement of the signal of the ultrasonic sensor, it can be provided that the at least one ultrasonic sensor is designed in such a way, in particular that the diameter and / or the frequency of the at least one ultrasonic sensor is selected in such a way that an intensity of the radiated ultrasonic waves of 50% can be achieved in a divergence angle range of θ=3.5° to θ=40°, in particular at a divergence angle of approximately θ=10°.According to one embodiment of a measuring arrangement according to the invention, which ensures a further improvement in the signal of the ultrasonic sensor-especially when used for examining polymer melts as material moving in the tubular body-it can be provided that the ultrasonic sensor has a frequency of 1 MHz to 10 MHz, in particular of 4 MHz.A measuring arrangement according to the invention can be designed in a particularly compact manner if the ultrasonic sensor is designed not only for emission, but at the same time also for detection of ultrasonic waves reflected from the material or the interior of the tubular body. In this way, the measuring arrangement advantageously makes do with a combined transmitter / receiver as an ultrasonic sensor, which is designed and suitable for simultaneously emitting and receiving reflected ultrasonic waves. A piezoelectric element or piezoelectric oscillator can advantageously be provided as the ultrasonic sensor, which simultaneously functions as a transmitter and as a detector for the reflected ultrasonic waves from the interior of the tubular body.According to one embodiment variant of a measuring arrangement according to the invention, which makes do with components of particularly simple construction, it can be provided that the measuring arrangement comprises at least one ultrasonic detector for receiving reflected ultrasonic waves from the material or the interior of the tubular body, wherein the ultrasonic detector is arranged in and / or on the outer jacket of the tubular body at an incoupling angle α of 1°<α≤89°, in particular 2°≤α≤ 70°, preferably 6°≤α≤ 25°, measured between the longitudinal axis of the ultrasonic sensor or detector and a straight line running normal to the longitudinal axis of the tubular body.According to one embodiment variant of a measuring arrangement according to the invention, which can be used for particularly varied measurements, it can be provided that the measuring arrangement comprises, in addition to the first ultrasonic sensor, at least one second or further ultrasonic sensor for emitting ultrasonic waves into the interior of the tubular body, wherein the further ultrasonic sensor is arranged in and / or on the outer jacket of the tubular body at an incoupling angle α of 1°<α≤89°, in particular at an incoupling angle α of 2° to 70°, preferably at an incoupling angle α of 6° to 25°, measured between the longitudinal axis of the further ultrasonic sensor and a straight line running perpendicular to the longitudinal axis of the tubular body in the outer jacket of the tubular body, wherein the further ultrasonic sensor is mirrored and / or arranged parallel to the first ultrasonic sensor in and / or on the outer jacket of the tubular body, and wherein provision is made in particular, the further ultrasonic sensor is also configured to detect reflected ultrasonic waves from the interior of the tubular body.In such an embodiment, the reception angle of the respective ultrasonic sensor is advantageously selected to be negative with respect to the coupling angle of the respective ultrasonic sensor. In this context, "mirrored" is understood to mean that the two ultrasonic sensors are positioned opposite one another at the same angle along the longitudinal axis of the tubular body, while "parallel" in this context is understood to mean that the two ultrasonic sensors are arranged adjacently and incident at the same coupling angle.According to an advantageous embodiment variant of a measuring arrangement according to the invention for use in conveyors of any kind, it can be provided that the tubular body is a conveyor with a conveying element, in particular with a conveying screw.According to an advantageous embodiment variant of a measuring arrangement according to the invention, which is particularly suitable for use in the processing and melting of polymeric materials, it can be provided that the tubular body is an extruder for processing and melting polymeric materials, having at least one screw rotatable in the tubular body and having a web running helically around a core, wherein the extruder comprises an intake region for introducing the material to be processed into the extruder and an extrusion region located further downstream for melting the material. Advantageously, the extruder comprises at least one extruder seal, e.g. a counter thread, wherein the measuring arrangement is arranged in the region of the at least one extruder seal. The arrangement of the measuring arrangement in the region of an extruder seal advantageously enables a particularly simple online checking of the extruder seal for tightness.According to an advantageous embodiment variant of a measuring arrangement according to the invention, it can be provided that the outer jacket of the tubular body comprises steel, in particular consists of steel. Due to the high density differences between steel and, for example, polymer as material moving in the tubular body, the following special feature results: the ultrasound obliquely coupled into the steel outer jacket of the tubular body is refracted towards the orthogonal direction of the longitudinal axis of the tubular body or a screw axis, if such a screw is present. It is thus possible to take delay measurements in the screw channel and to amplify the signals far more strongly than in the case of coupling at an angle α of 0°.The invention further relates to a measuring arrangement according to the invention which is designed for determining ultrasonic measurement data of a polymer or a polymer melt which is present in the tubular body during processing, in particular extrusion, wherein the polymer has a dynamic viscosity η of 0 to 500 000 Pa*s, in particular of 50 to 300,000 Pa*s. Such a measuring arrangement is particularly suitable for use in the processing and melting of polymeric materials.In an advantageous embodiment, a measuring arrangement according to the invention or one of the ultrasonic sensors is arranged on or in melt lines, melt guides or melt filters, wherein the melt flow or the direction of the melt conveyed therein via pressure is measured and further parameters can be determined or controlled therefrom. Thus, for example, by measuring the conveying direction in the case of back-flushable filters, it can be detected whether and how well the back-flushing functions.In an embodiment advantageous in particular for the treatment of polymers, a measuring arrangement or one of the ultrasonic sensors is arranged close to an extruder seal between the inlet and outlet channels of a melt filter in the extruder, where the rollover is prevented by back-feeding material by a back-feeding thread in this region.In a further advantageous embodiment, a measuring arrangement or one of the ultrasonic sensors in the extruder is arranged at the material intake zone downstream of the gearbox, wherein the screw seal installed there ensures that neither plastic material nor moisture and dust can block the toothing or cause corrosion by continuous return.In yet another advantageous embodiment, a measuring arrangement or one of the ultrasonic sensors is arranged on threaded shaft seals in a melt pump which specifically uses melt for lubricating the shaft in the threaded shaft seal. The function of the shaft seal is to float the shaft on the melt therein without using and losing excessive plastic material therefor and to seal the housing outwardly. In order to ensure this in a controlled manner, the shaft seals are designed on the basis of the viscosity of the conveying medium and, if required, are cooled in partial regions of the shaft seal in order to produce a seal by the hardened plastic film. However, the seals are limited by the suction pressure and the viscosity of the conveying medium. Leaks are produced as a result of an inevitably occurring wear which is caused by contamination or cracking during the feed of recycling material, which has the consequence that the suction effect or cooling is no longer sufficient for a correct sealing and plastics material is lost in an uncontrolled manner. The online monitoring with the measuring arrangement according to the invention can contribute to detecting these leaks and to initiating targeted countermeasures.It is furthermore an advantageous object to provide a method with which it is possible in a simple manner during operation of a conveyor or extruder, for example, to reliably obtain high-quality ultrasonic measurement data from the material moved in the interior of a tubular body.The object is achieved in that at least one measuring arrangement for ascertaining ultrasonic measurement data from the interior of a tubular body, in particular ultrasonic measurement data of a material moving in the tubular body, is provided and used in the method, in particular a measuring arrangement according to the invention described above. The measuring arrangement comprises a tubular body with an outer jacket and at least one ultrasonic sensor or ultrasonic transmitter for emitting ultrasonic waves into the interior of the tubular body, wherein the ultrasonic sensor is arranged in and / or on the outer jacket of the tubular body at an incoupling angle α of 1°<α≤89°, measured between the longitudinal axis of the ultrasonic sensor and a straight line running perpendicular to the longitudinal axis of the tubular body. The oblique coupling brings about an avoidance or attenuation of the first reflection and an ultrasonic sensor with higher power can advantageously be used.An advantageous object is furthermore to provide a method with which it is possible in a simple and reliable way online during operation of e.g. a conveyor or extruder to determine the flow direction of a material moving in a tubular body.The object is achieved by a method for online determination of the flow direction of a material moving, in particular conveyed, in a tubular body, wherein at least one measurement arrangement is provided and used for determining ultrasonic measurement data from the interior of a tubular body, in particular ultrasonic measurement data of a material moving in the tubular body, wherein the measurement arrangement comprises a tubular body having an outer jacket and at least one ultrasonic sensor or ultrasonic transmitter for emitting ultrasonic waves into the interior of the tubular body, wherein the ultrasonic sensor is arranged in and / or on the outer jacket of the tubular body at an incoupling angle α of 1°<α≤89°, measured between the longitudinal axis of the ultrasonic sensor and a straight line running perpendicular to the longitudinal axis of the tubular body, in particular by means of or using one of the measurement arrangements according to the invention described above. The method comprises the following steps:a highly compacted, molten, paste-like or liquid material is moved or conveyed inside the tubular body, for example a conveyor, extruder or a pipeline,emitting ultrasonic waves into the moving material or into the interior of the tubular body,a repeated recording of the ultrasonic transit times of ultrasonic waves reflected at inhomogeneities in the material and / or inhomogeneities in the material from the interior of the tubular body over a predetermined measurement duration during the movement or conveying,determining the flow direction of the material relative to the ultrasonic sensor of the measuring arrangement based on the determined travel time shift of at least one respective non-homogeneity over several repeated measurements and the known geometric arrangement of the ultrasonic sensor relative to the tubular body.In connection with the invention, "inhomogeneities" are understood to mean any detectable deviations within the material or the material itself. This is thus understood to mean inhomogeneities which occur in the material, for example a melt, which is moved or conveyed in the tubular body, that is to say particles, gas bubbles, water or contaminants, for example, but also inhomogeneities which relate to the material, for example the melt, itself, such as material portions which have density, pressure and / or temperature differences with respect to the remaining material.In connection with the invention, a "transit time shift" is understood to mean that the transit time, which exhibits ultrasonic waves reflected on a particle, for example, toward the ultrasonic sensor or the ultrasonic detector, shifts over several measurements depending on the direction of movement of the particle, i.e., shortens or lengthens.The determination of the actual direction of flow of the material has substantial advantages in making sure that a tubular body is sealed, or in the effect of any seal arranged in the tubular body. In comparison with known measurements of the tightness of screw seals via the differential pressure, the determination of the flow direction by means of ultrasound has the advantage that it is independent of the calibration of the sensor system used. Nor is the measurement of the flow direction subject to long-term drift or wear.Further advantageous embodiment variants of the method are described in the dependent claims.According to an advantageous variant of the method, it can be provided that the flow direction of the material is determined on the basis of the slopes of the reflections of the ultrasonic waves reflected at at least one respective non-homogeneity or on the basis of reflections of the ultrasonic waves reflected at at least one respective non-homogeneity and the slope resulting therefrom in a representation of the ultrasonic transit time plotted over the measurement duration. It is particularly simple and reliable for determining the direction of flow to use multiple reflection, since this ensures a higher sensitivity. The slope of the curves becomes greater for each reflection, since the differences in the transit times are multiplied on account of, for example, pressure and thus density differences in the material.The evaluation can be carried out particularly easily on the basis of the determined travel time shift if, in order to determine the flow direction of the material, the ultrasonic travel time of the ultrasonic waves reflected at at least one respective non-homogeneity is represented as a travel time profile plotted over the measurement duration.In this context, a further simplification of the evaluation and, in particular, a particularly rapid, automated evaluation can be made possible if the runtime profile is present as an image file, wherein it is provided in particular that image processing algorithms are used for evaluating the gradient of the reflections of the ultrasonic waves reflected at at least one respective non-homogeneity.In the case of an orientation of the ultrasonic sensor counter to the normal flow direction, for example, a positive slope can be recognized as an oncoming flow (desired state) and a negative slope as a flowing-away flow (malfunction). In the case of an orientation of the ultrasonic sensor in the flow direction, it can behave in the opposite direction.According to an advantageous variant of the method, which is particularly suitable for use in the processing and melting of polymeric materials, it can be provided that a polymer, e.g. a polymer melt, which is in processing, in particular extrusion, is conveyed as material in the tubular body, wherein the polymer has a dynamic viscosity η of 0 to 500 000 Pa*s, in particular of 50 to 300,000 Pa*s.A method can be carried out particularly reliably and in a time-saving manner if a measuring arrangement designed according to the invention is used.According to an advantageous variant of a method, which is particularly suitable for use in conveyors of any kind, it can be provided that the material is conveyed in the interior of a tubular body designed as a conveyor with a conveying element, in particular with a conveying screw.According to an advantageous variant of a method, which is particularly suitable for use in the processing and melting of polymeric materials, it can be provided that the material is conveyed inside a tubular body designed as an extruder for processing and melting polymeric materials, with at least one screw that can be rotated in the tubular body and has a web that runs helically around a core, wherein the extruder comprises an intake region for introducing the material to be processed into the extruder and an extrusion region located further downstream, in particular with at least one extruder seal for melting the material, and wherein the measuring arrangement is arranged in the region of the at least one extruder seal.A method for processing, in particular for recycling, a polymer is also provided, wherein the polymer is melted and a method is used for online determination of the flow direction of the polymer.Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.The invention is schematically illustrated in the drawings below with reference to particularly advantageous, but not restrictive, exemplary embodiments and is described by way of example with reference to the drawings.The following show schematically: FIG. 1 shows an exemplary embodiment of a known arrangement of an ultrasonic sensor on a tubular body, FIG. 2 shows a schematic view of an exemplary embodiment of a measuring arrangement according to the invention for ascertaining ultrasonic measurement data from the interior of a tubular body, FIG. 3 shows an example of the pulse voltage plotted against the running time in the exemplary embodiment from FIG. 1, FIG. 4 shows an example of the pulse voltage after subtraction of the first reflection on the inner wall of the tubular body plotted against the transit time in the exemplary embodiment from FIG. 1, FIG. 5 shows a schematic view of a further exemplary embodiment of a measuring arrangement according to the invention, FIG. 6 shows a schematic view of a further exemplary embodiment of a measuring arrangement according to the invention, FIG. 7 shows a further perspective view of an exemplary embodiment of a measuring arrangement according to the invention, FIG. 8 shows a further perspective view of an exemplary embodiment of a measuring arrangement according to the invention, FIG. 9 shows a schematic illustration of a measuring arrangement according to the invention with an incoupling angle α and divergence angle θ, distance Ds of the ultrasonic sensor from the inner wall of the tubular body, FIG. 10 shows a schematic illustration of the relationship between ultrasonic intensity and divergence angle θ, and of the geometry of the ultrasonic sensor, FIG. 11 shows a representation of the relationship of the coupling angle in steel α St and the refraction angle in polymer melt α Sch at temperature- and pressure-dependent sonic speeds in the melt, FIG. 12 shows a first schematic illustration of the relationship between the coupling angle α, the distance Ds and the incident beam surface or projection surface with axis length b, FIG. 13 shows a second schematic illustration of the relationship between the coupling angle α, the distance Ds and the incident beam surface or projection surface with axis length b, FIG. 14 shows a representation of the relationship between the coupling angle in steel α St and the refraction angle in polymer melt α Sch, FIG. 15 shows a representation of the relationship between the coupling angle in steel α St and the refraction angle in polymer melt α Sch at various temperature-dependent sonic speeds in the steel, FIG. 16a is a schematic illustration of the inferred flow direction of the material in a tubular body, FIG. 16 bshows a schematic illustration of the pressure plotted against the channel position in the tubular body from FIG. 16 a, FIG. 16 cshows a schematic representation of the speed of sound plotted against the channel position in the tubular body from FIG. 16 a, FIG. 17 shows an exemplary embodiment of a runtime profile for deriving the flow direction. FIG. 18a is a schematic illustration of the path of travel of the ultrasound when observing a particle with a flow direction from left to right, FIG. 18 bshows a schematic illustration of the travel path of the ultrasound when observing a particle with a flow direction from right to left, FIG. 19a is a schematic illustration of the ultrasonic path between the ultrasonic sensor and a particle with flow direction from left to right. FIG. 19 bshows a schematic illustration of the ultrasonic travel path between ultrasonic sensor and a particle with flow direction from right to left. FIG. 20 ashows a schematic representation of the ultrasound transit time plotted against the measurement number for the example from FIGS. 18 aand 19 a, FIG. 20 bshows a schematic representation of the ultrasound transit time plotted against the measurement number for the example from FIGS. 18 band 19 b, FIG. 21 a shows a runtime profile in the form of an image file for the example from FIGS. 18 aand 19 a, FIG. 21 bshows a runtime profile in the form of an image file for the example from FIGS. 18 band 19 b, FIG. 22 shows a schematic illustration of the evaluation of the flow direction on the basis of the runtime profiles from FIGS. 21 aand 21 b. FIGS. 23a, b and c show the arrangement of one or more ultrasonic sensors.FIG. 1 shows an exemplary embodiment of a known arrangement of an ultrasonic sensor or ultrasonic transmitter 1 on a tubular body 2. The cylinder wall of the tubular body 2 is made of steel in the embodiment example. As can be seen in FIG. 1, ultrasonic measurements on extruders and plasticizing units are realized there in such a way that the ultrasonic sensor 1 is mounted orthogonally on the cylinder or screw axis. In the known arrangement, the ultrasonic signal is thus coupled orthogonally into the cylinder wall and further into the polymer melt 3.However, a disadvantage of such an arrangement of the ultrasonic sensor 1 on the tubular body 2 is that the amplification is limited by the strong reflection on the inner wall of the cylinder. This is schematically illustrated in FIG. 3. FIG. 3 shows the pulse voltage V plotted against the delay time dt in the voltage input range ADC. The ultrasonic signal may only be amplified to such an extent that the reflection remains within the voltage input range ADC. After subtraction of the first reflection on the inner wall of the tubular body 2 or the cylinder wall reflection, only a very small signal of the melt channel or of the polymer melt 3 remains in the range of 3-5% of the cylinder wall amplitude.If this first reflection is omitted, this restriction is omitted and the sensor signal becomes better, since it can be amplified significantly higher. This "omission" or a reduction of the first reflection at the cylinder inner wall is achieved in a measuring arrangement 100 according to the invention in that the coupling angle α-measured between the longitudinal axis of the ultrasonic sensor 1 and a straight line running perpendicular to the longitudinal axis of the tubular body 2-is selected to be 1°<α≤89° and the ultrasonic sensor 1 is arranged obliquely in or on the outer jacket of the tubular body 2. Ideally, the coupling angle α lies in a range from 2° to 70° (2°≤α≤70°), optimally in a range from 6° to 25° (6°≤α≤25°), This is illustrated in FIG. 2, where the coupling of the ultrasonic signal of the ultrasonic sensor 1 into the cylinder wall of the tubular body 2 made of steel takes place specifically at a coupling angle α st of 45°.The oblique coupling has the advantage that the first very intensive acoustic wave reflection is not reflected directly back to the sensor. This allows higher ultrasonic energies to be selected, which would normally overload the ultrasonic detector or the combined ultrasonic transmitter / detector. At the same time, the reflections of the worm can still be observed.To achieve this, angles of, for example, 1° ≤ α ≤ 89° are well usable, angles of 2° ≤ α ≤ 70° are favorable, and angles of 6° ≤ α ≤ 25° are most suitable. These angles result from various tests on the temperature and pressure stability of the refraction angle during the transition into the melt.Furthermore, the spacing Ds of the ultrasonic sensor 1 from the inner wall of the extruder is important, since this spacing defines the sound surface of the surface incident on the boundary surface as a function of the angle α. This should be optimally larger than the blind area of the ultrasonic sensor 1 (>17 mm) and smaller than the available material thickness of the extruder. The farther the ultrasonic sensor 1 is from the inner wall of the extruder, the greater the acoustic length b of the acoustic surface or projection or irradiation surface becomes, with the coupling angle α remaining the same, but with the divergence angle θ. The greater this becomes, the less energy can couple into the melt region of the extruder.Geometric relationships have been used to develop a formula for the above description, which ensures general validity over all extruder sizes (see FIG. 9 ): the divergence angle θ being given by the formula:The ratio b / Ds thus results in a range of 0.001-1, in particular 0.01-0.95, or particularly advantageously 0.016-0.90: wherein k=0.56 is an experimental constant with which the divergence angle becomes so large that approximately 50% of the emitted ultrasonic energy lies in the cone, and wherein λ is the ultrasonic wavelength (depending on the excitation frequency 1-10 MHz), and wherein D is the sensor width.An advantage of the coupling angle 1°<α≤89° is the non-present or at least significantly weaker first reflection of the cylinder inner wall. This reflection is very strong when the coupling is 90° to the longitudinal axis of the tubular body 2 (α=0°), and the ultrasonic signal can only be amplified as much as the input voltage range allows. The first reflection would overlap all other reflections. If this first reflection is omitted, this restriction is omitted and the ultrasonic sensor signal becomes better, since it can be amplified significantly higher. By avoiding or attenuating the first reflection, an ultrasonic sensor 1 with higher power can advantageously also be used.In a range of the coupling angle α of 6°-25°, the refraction angle behaves linearly (see FIG. 14 ), particularly also with changes of pressure and temperature (see FIGS. 11 and 15 ). At lower angles < 6° there is hardly any advantage with respect to the first reflection (see FIGS. 12 and 13 ). At higher angles > 25°, the ultrasonic energy is again distributed strongly over the large cut surface of the sound cone, and the reflected proportion also increases in %. This advantageously entails more inhomogeneities in the sound cone, but a correspondingly lower reflection intensity must be taken into account, which can make detection more difficult. Physically, the maximum in total reflection.In addition, a larger range can be scanned by the oblique coupling and, for example, changes in the wear of the extruder can be identified more precisely (see FIGS. 12 and 13 ). The higher the coupling angle, the broader the examined area, or the more information the reflected measurement signal contains. The automated evaluation thus potentially also recognizes more inhomogeneities, whereby the accuracy of the result increases. With the coupling angle, the proportion of the detected periodic reflections decreases and the sound path covered to the measurement point increases, which has a positive effect on the signal interpretation in each case. Both effects increase the time interval between detected reflections and thus the time in which other information can be obtained.A further advantage which results in particular in the pairing of steel / plastic is that the large differences between steel and plastic lead to very small refraction angles and the measurement results (e.g. gap width) are thus comparable to the classic coupling-in.Due to the high density differences between the tubular body 2 made of steel and the plastic or polymer melt 3, the following special feature arises: the ultrasound obliquely coupled into the cylinder steel is refracted at a refraction angle α Sch toward the orthogonal direction of the screw axis. It is thus possible to take time of flight measurements in the screw channel and to amplify the ultrasonic signals far more strongly than in the case of conventional orthogonal coupling.The following table shows an overview of sound velocities and refraction angles α Sch at different polymer types, pressures and temperatures:PPPEPET250° C., 5 bar857 m / s949 m / s1108 m / s350° C., 280bar882 m / s927 m / s1078 m / sAngle α:PPPEPET250° C., 5 bar5,94°6,58°7,7°350° C., 280bar6,13°6,44°7,5°Average PP,PE,PET: 6.7°The relationship between the angle of injection in steel (45° in the example) and the angle of refraction in the polymer is given by the following relationship:FIG. 15 shows the relationship of the angles α St and α Sch at different temperature-dependent sound speeds in the steel. It is thereby shown that the deviations are negligible. FIG. 15 shows the ultrasonic velocity in the steel, assumed at room temperature, medium temperature and up to a maximum of 350° C.-represented by the three curves. In FIG. 15, the coupling angle α St is plotted on the x-axis. On the y-axis, the associated refraction angle α Sch of the sound wave in the melt is found after it has been refracted at the transition. The acoustic wave is refracted from the dense medium to the thin to the solder, which is recognizable by the different axis scaling.FIG. 11 shows the relationship of the angles at temperature- and pressure-dependent sonic speeds in the melt, wherein the p- and T-regions correspond to typical plastic recycling installations. It is found that the deviations become larger, but are acceptable in the defined measurement range from 6° to 25°. For this diagram it is assumed that the steel temperature is the same, but the melt temperature or the pressure changes. In addition, the curves are averaged over different polymers. x- and y-axes are to be understood as in FIG. 15.FIG. 5 shows a schematic view of a further exemplary embodiment of a measuring arrangement 100 according to the invention. In FIG. 5, the integration of the ultrasonic sensor 1 into the outer jacket of the tubular body 2 is achieved by providing a milled or rotated oblique surface in the outer jacket.FIG. 6 shows a schematic view of a further exemplary embodiment of a measuring arrangement 100 according to the invention. In FIG. 6, the integration of the ultrasonic sensor 1 into the outer jacket of the tubular body 2 is achieved by providing a blind bore and a thread for the fastening of the ultrasonic sensor 1 in the outer jacket.FIGS. 7 and 8 show the specific configuration of a measuring arrangement 100 according to the invention on an extruder for processing and melting polymeric materials, having a screw rotating in the tubular body 2 with a web running helically around a core. In the exemplary embodiments, the extruder has an intake region (not shown here) for introducing the material to be processed into the extruder and an extrusion region located further downstream for melting the material. There, an extruder seal in the form of a return or build-up element is also provided, and the measuring arrangement 100 is arranged in the region of the extruder seal of the extruder. The sealing thread can be seen from the fact that it is in the opposite direction to the thread of the remainder of the extruder. The ultrasonic sensor 1 does not have to be arranged at the position indicated in FIG. 7 or 8, but can advantageously also be arranged in the region close to the sealing thread. As described further below, a second or further ultrasonic sensor can also be installed in this region. The inclusion of the ultrasonic sensor 1 in FIGS. 7 and 8 corresponds to the exemplary embodiments of FIGS. 5 and 6, respectively.Examples of an optimized power range or an optimized intensity of the ultrasonic sensor 1 used for a combination of steel and polymer melt 3 are 0.001 W / cm 2- 2 W / cm 2. A lower power prevents the detection of inhomogeneities in the polymer melt 3.2 W / cm 2 is already in the range of the power noise and higher powers would already damage the polymer. An example range for an optimized frequency of the ultrasonic sensor 1 used for a combination of steel and polymer melt 3 is 1 MHz-10 MHz.In the exemplary embodiments shown of a measuring arrangement 100 according to the invention, the distance of the ultrasonic sensor 1 from the "measuring point" in the polymer melt 3 is selected to be greater than the near-field length of the ultrasonic sensor 1, that is to say greater than 10 mm, for example 17 mm. The distance of the ultrasonic sensor 1 from an irradiation surface which, at the transition of the outer jacket of the tubular body 2 to the interior of the tubular body or to the polymer melt 3, has a length, in the exemplary embodiment a main axis length, b of 0.6 to 35 mm at an incoupling angle α of 6° to 25° is therefore selected to be greater than the near field length of the ultrasonic sensor 1, in particular greater than 10 mm, preferably 17 mm.The region of sound focusing, which is characterized by interference with maxima and minima of the sound pressure, is referred to as the near field. The end of the near field in the sound propagation direction is defined by the last maximum of the sound pressure amplitude distribution. In the near field, there is natural focusing of the sound field. The distance at which the near field merges into the far field is the near field length. It depends on the size of the vibrator and on the wavelength in the specimen.Furthermore, in the exemplary embodiments, the ultrasonic sensor 1 is designed such that its diameter D and its frequency f are selected such that an intensity I of the radiated ultrasonic waves of 50% is achievable in a divergence angle range of θ=3.5° to θ=40° (3.5°≤θ≤40°, optimally at a divergence angle of approximately or exactly 10°.The divergence angle θ is calculated according to the following relationship:K... Constantλ... wavelength (λ=c / f)c... Speed of Soundf...frequencyAs can be seen in FIG. 10, the ultrasonic intensity in the sound cone emitted by the ultrasonic sensor 1 is not constant. It decreases towards the outside. If possible, measurement should not be carried out within the near field, since there are severe intensity fluctuations.Some calculation examples for the optimized divergence angles θ for a combination of a tubular body 2 made of steel and polymer melt 3 in the interior of the tubular body 2 are summarized below. Ultrasonic sensor 1 is designed as a piezoelectric oscillator.Piezooscillator is a piezooscillator◯ D=10 mm◯ f = 4 MHzSchallgeschwindigkeiten◯ C Stahl= 5880 m / s◯ C Polymer= 1000 m / sCalculations• Wavelength:◯• Divergence angle:◯◯◯• Near-field length:◯Refraction InterfaceThe angles indicated here relate to the coupling angle α St into the steel. In the transition to the melt, an angle change occurs due to refraction at a refraction angle α Sch.In the exemplary embodiment, a piezoelectric element or piezoelectric oscillator is used as the ultrasonic sensor 1, the ultrasonic sensor 1 simultaneously acting as a detector for the reflected ultrasonic waves from the interior of the tubular body 2.The measuring arrangement 100 according to the invention can also comprise, with the ultrasonic sensor 1, an ultrasonic detector for receiving reflected ultrasonic waves from the interior of the tubular body 2, wherein the ultrasonic detector is arranged in and / or on the outer jacket of the tubular body 2 at an angle α of ≤89° between the longitudinal axis of the ultrasonic detector and a straight line running normal to the longitudinal axis of the tubular body.An ultrasonic sensor 1, which simultaneously functions as a detector, or an ultrasonic sensor 1 and an ultrasonic detector, are basically sufficient for the above-mentioned measurements, such as, for example, flow direction measurements.In a measuring arrangement 100 according to the invention, not only a single ultrasonic sensor 1 (FIG. 23 a) but also two or more ultrasonic sensors 1 can be provided, in particular if more complex measurements are to be carried out: for example, two or more ultrasonic sensors 1 can be used for advantageous measurements or conclusions of wear, the worm deflection or a worm pendulum movement, but also for flow direction detection and flow direction estimation together with estimation of the swirl of the melt in the worm turn. The second ultrasonic sensor 1 can either be arranged in a mirrored manner along a normal to the longitudinal axis, i.e. opposite one another at the same angle (FIG. 23 b ) or arranged in parallel at the same angle directly next to the first ultrasonic sensor 1 along the longitudinal axis, i.e. radiating next to one another at the same coupling angle (FIG. 23 c ).The distance of the ultrasonic sensors from one another on the basis of the longitudinal axis of the tubular body is 0-0.2 L / D in parallel operation, wherein the ultrasonic sensors should in principle be positioned as close to one another as possible. The distance of the sensors from one another on the basis of the longitudinal axis of the tubular body is 0-2 L / D, in particular 0-1 L / D, in mirrored operation.As already mentioned above, it is possible with a measuring arrangement 100 according to the invention with an ultrasonic sensor 1 to obtain high-quality ultrasonic signals quickly and easily and thus then to carry out a wide variety of measurements in a tubular body 2 such as an extruder with a screw. The ultrasonic sensor 1 is arranged here optimally along the flight (in the pitch direction, see FIGS. 7 and 8 ).FIG. 16a shows, indicated at the top, the cylinder or tubular body 2, in gray, the melt and at the bottom the extruder screw with webs. The direction of flow goes from right to left. Three longitudinal positions are marked to better illustrate the ultrasonic velocity intervals. FIG. 16 bshows the pressure p in the y direction. In the case of conveying screws of the plastics processing, the pressure in the screw channel falls off almost linearly from the active (driving) flank to the passive flank. After this, the pressure rises again linearly via the screw flight (from the passive to the active flank) (see FIG. 16 b ).The ultrasonic transit time in plastic melts decreases almost linearly with increasing pressure (ultrasonic velocity increases, see FIG. 16 c ) or increases with increasing melting temperature (ultrasonic velocity decreases, see FIG. 16 b ). It is therefore possible to draw conclusions as to the pressure profile directly from the ultrasonic transit time, particularly exactly on the assumption that the melt temperature in the channel is relatively constant. Thus, inhomogeneities in plastic melts can be detected with ultrasound. FIG. 16 cillustrates the direct relationship between the pressure p in the melt and the ultrasonic velocity c, which is depicted on the y-axis. Accordingly, a plurality of velocity patterns can be distinguished in the detected ultrasonic signal; FIG. 17 shows real data of such a measurement here.Based on these circumstances, it was possible to develop a method for online determination of the flow direction of a material moving in a tubular body 2, on which method a measuring arrangement 100 according to the invention, as described above, for example, is arranged.In an exemplary embodiment which enables the online determination of the flow direction of a polymer melt 3 moving in a cylindrical extruder, the following method steps are provided, for example:moving or conveying material, such as, for example, compressed material pieces, partially molten, molten, pulpy or liquid material, in the interior of the tubular body 2, for example in the interior of an extruder for processing and melting polymeric materials having at least one screw rotatable therein, in the context of recycling processing of a polymer, wherein the polymer is molten and thus moves through the extruder as a polymer melt 3,delivering ultrasonic waves into the interior of the extruder or material during the movement or conveying of the polymer melt 3,repeatedly recording the running time of ultrasonic waves reflected at inhomogeneities in the conveyed polymer melt 3 and / or inhomogeneities in the conveyed polymer melt 3 from the interior of the extruder over a predefined measurement duration during the conveying, anddetermining the flow direction of the polymer melt 3 relative to the ultrasonic sensor 1 of the measuring arrangement 100 based on the determined delay time shift of at least one respective non-homogeneity over a plurality of repeated measurements and the known geometric arrangement of the ultrasonic sensor 1 relative to the extruder.The movement of a respective non-homogeneity relative to the ultrasonic sensor 1 is thus tracked by means of the corresponding ultrasonic transit times over a predefined measurement duration or a predefined observation period, as is schematically shown in FIGS. 18 a, 18 b, 19 aand 19 b.Such "inhomogeneities" can be inhomogeneities which occur as a quasi foreign body within a more or less homogeneous polymer melt 3, that is to say particles, gas bubbles, water or contaminants, for example. "inhomogeneities" can, however, also be inhomogeneities of the otherwise homogeneous polymer melt 3, such as melt fractions which have pressure and / or temperature differences compared to the remaining polymer melt 3 conveyed.FIG. 18 ashows the travel path of the ultrasound when observing a particle which moves past the ultrasound sensor 1 in the interior of the tubular body 2 or of the extruder with flow direction FR from left L to right R. FIG. 19 aschematically shows the ultrasonic travel path between ultrasonic sensor 1 and particles when moving in the flow direction FR from left L to right R. L M,n thereby indicating the acoustic travel path during a measurement n. The sound travel path L M,n increases from the first measurement n=1 to the third measurement n=3. The increase in the transit time is also shown by the arrow in FIG. 20a, where the ultrasonic transit time dt is plotted against the measurement number No.FIG. 18 bshows the travel path of the ultrasound when observing a particle which moves past the ultrasound sensor 1 in the interior of the tubular body 2 or of the extruder with flow direction FR from right R to left L. FIG. 19 bshows schematically the ultrasonic travel path between ultrasonic sensor 1 and particles during movement with flow direction FR from right R to left L. L M,n in this case again indicates the acoustic travel path during a measurement n. The sound travel path L M,n decreases from the first measurement n=1 to the third measurement n=3. The decrease in the transit time is also shown by the arrow in FIG. 20 b, where the ultrasonic transit time dt is plotted against the measurement number No.Tests on the seal have shown that the flow direction FR of the material in the screw cross section can be determined particularly reliably on the basis of the slopes of the reflections of the ultrasonic waves repeatedly reflected at a respective non-homogeneity in a representation of the ultrasonic transit time dt plotted over the measurement duration MD. FIGS. 21 aand 21 b show, for the examples from FIGS. 18 aand 18 b, such a representation in the form of a runtime profile which is processed as an image file. The individual lines or curves in FIGS. 21 aand 21 brepresent individual inhomogeneities and for a selected non-homogeneity the trend of the ultrasonic transit time dt is symbolically shown with an arrow. If such a runtime profile is present as an image file, a wide variety of known image processing algorithms, such as 2D FFT, for example, can naturally be used for evaluating the slope.It is optimally known whether the measurement is carried out in a pressure-consuming region (negative pressure gradient Ip) or in a pressure-building region (positive pressure gradient hp) or in which region the ultrasonic sensor 1 is arranged in the tubular body 2.FIG. 17 shows real measurement data of an ultrasonic measurement. The measurement duration MD is plotted on the x-axis, and the propagation time dt of the detected ultrasonic signals or the propagation time of the reflected wave is plotted on the y-axis. The slope shown increases with each reflection because the acoustic wave traverses the melt twice more per reflection signal. The speed difference between high and lower pressure in the melt thus comes to bear again on each reflection.The use of multiple reflection (see FIG. 17 ) is therefore advantageous for the evaluation, since a higher sensitivity can be utilized in this case. The slope of the curves becomes greater for each reflection, since the differences in the transit times due to the pressure and thus density differences in the material are multiplied.FIG. 22 schematically shows the evaluation of the flow direction FR on the basis of the runtime profiles in FIGS. 21 aand 21 b. Depending on the gradient, a flow direction FR is determined from left L to right R (decreasing) or from right R to left L (increasing).The information on the actual direction of flow FR of the material has substantial advantages in making confidence in the effect of the seal (constant measurement).References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 2 558 263

[0003] EP 2 689 908

[0003]

Claims

Measuring arrangement for determining ultrasonic measurement data from the interior of a tubular body, in particular ultrasonic measurement data of a material moving in the tubular body, wherein the measuring arrangement (100) comprises a tubular body (2) having an outer jacket and at least one ultrasonic sensor or ultrasonic transmitter (1) for emitting ultrasonic waves into the interior of the tubular body (2), wherein the ultrasonic sensor (1) is arranged in and / or on the outer jacket of the tubular body (2) at an incoupling angle α of 1° < α ≤ 89°, measured between the longitudinal axis of the ultrasonic sensor (1) and a straight line running normal to the longitudinal axis of the tubular body (2).Measuring arrangement (100) according to Claim 1, characterized in that the ultrasonic sensor (1) is arranged at an incoupling angle α of 2° to 70°, in particular at an incoupling angle α of 6° to 25°, in and / or on the outer jacket of the tubular body (2).Measuring arrangement (100) according to Claim 1 or 2, characterized in that the distance of the ultrasonic sensor (1) from an irradiation surface and / or projection surface at the transition of the outer jacket of the tubular body (2) to the interior of the tubular body (2), which is dependent on the coupling angle α and the ultrasonic frequency, is greater than the near-field length of the ultrasonic sensor (1), in particular greater than 10 mm, preferably 17 mm.Measuring arrangement (100) according to one of the preceding claims, characterized in that the distance Ds, measured from the centre of the ultrasonic sensor (1) normal to its irradiation surface and / or projection surface, which has a length, in particular a main axis length, at the transition of the outer jacket of the tubular body (2) to the interior of the tubular body (2), is given by: b D S = sin θ cos 2 ( ≅ ) - s i n 2 ( θ 2 ) wherein the divergence angle θ is given by the formula: θ = a r c s i n ( k ≥ λ D ) wherein k = 0.56 is an experimental constant, λ is the ultrasonic wavelength and D is the width and / or the diameter of the ultrasonic sensor (1).Measuring arrangement (100) according to Claim 4, characterized in that the ratio b / Ds of the length, in particular of the main axis length, b of the incident radiation surface and / or projection surface to the distance Ds of the ultrasonic sensor (1) is in a range from 0.001 to 1, in particular from 0.01 to 0.95, preferably from 0.016 to 0.9.Measuring arrangement (100) according to one of the preceding claims, characterized in that the at least one ultrasonic sensor (1) is designed in such a way that the diameter and / or the frequency of the at least one ultrasonic sensor (1) is selected in such a way that an intensity of the radiated ultrasonic waves of 50% can be achieved in a divergence angle range of θ=3.5° to θ=40°, in particular at a divergence angle θ=10°.Measuring arrangement (100) according to one of the preceding claims, characterized in that the ultrasonic sensor (1) has a frequency of 1 MHz to 10 MHz, in particular a frequency of 4 MHz.Measuring arrangement (100) according to one of the preceding claims, characterized in that the ultrasonic sensor (1) is designed for detecting reflected ultrasonic waves from the interior of the tubular body (2) or as an ultrasonic detector.Measuring arrangement (100) according to one of the preceding claims, characterized in that the measuring arrangement (100) comprises at least one ultrasonic detector for receiving reflected ultrasonic waves from the interior of the tubular body (2), wherein the ultrasonic detector is arranged in and / or on the outer jacket of the tubular body (2) at an incoupling angle α of 1° < α ≤ 89° measured between the longitudinal axis of the ultrasonic sensor (1) or ultrasonic detector and a straight line running normal to the longitudinal axis of the tubular body (2).Measuring arrangement (100) according to one of the preceding claims, characterized in that the measuring arrangement (100) comprises at least one further ultrasonic sensor (1) for emitting ultrasonic waves into the interior of the tubular body (2), wherein the further ultrasonic sensor is arranged in and / or on the outer jacket of the tubular body (2) at an incoupling angle α of 1° < α ≤ 89°, in particular at an incoupling angle α of 2° to 70°, preferably at an incoupling angle α of 6° to 25°, measured between the longitudinal axis of the further ultrasonic sensor and a straight line running normally to the longitudinal axis of the tubular body (2), wherein the further ultrasonic sensor is arranged in mirrored and / or parallel to the ultrasonic sensor (1) in and / or on the outer jacket of the tubular body (2), and wherein it is provided in particular that provision is made, the further ultrasonic sensor (1) for detecting reflected ultrasonic waves is also formed from the interior of the tubular body (2).Measuring arrangement (100) according to one of the preceding claims, characterized in that the tubular body (2) is a conveyor with a conveying element, in particular with a conveying screw, preferably an extruder, or a part or subsection of a conveyor or extruder.Measuring arrangement (100) according to one of the preceding claims, characterized in that the tubular body (2) is part of an extruder for processing and melting polymeric materials, having at least one screw which can be rotated in the tubular body (2) and has a web which runs helically around a core, wherein the extruder comprises an infeed region for introducing the material to be processed into the extruder and an extrusion region, which is situated further downstream, for melting the material, wherein the extruder preferably comprises at least one extruder seal and the measuring arrangement is arranged in the region of at least one of the extruder seals.Measuring arrangement (100) according to one of the preceding claims, characterized in that the outer jacket of the tubular body (2) comprises steel, in particular consists of steel.Measuring arrangement (100) according to one of the preceding claims, characterized in that the measuring arrangement (100) is designed to determine ultrasonic measurement data of a polymer which is present in the tubular body (2) during processing, in particular extrusion, wherein the polymer has in particular a dynamic viscosity η of 0 to 500 000 Pa*s, in particular of 50 to 300 000 Pa*s.Measuring arrangement (100) according to one of the preceding claims, characterized in that the at least one measuring arrangement (100) or the at least one ultrasonic sensor (1) is arranged on or in melt lines, melt guides or melt filters, or in an extruder directly next to an extruder seal or a return thread, in particular between the inlet and outlet channel of a melt filter, or in the material feed zone of an extruder, or directly next to threaded shaft seals in a melt pump.Conveyor or extruder for processing or melting polymer material comprising at least one measuring arrangement (100) according to one of claims 1 to 15.

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