Measuring arrangement and method for determining ultrasonic measurement data

Abstract

The invention relates to a measuring arrangement for determining ultrasonic measurement data from the interior of a tubular body, in particular ultrasonic measurement data relating to a material moving in the tubular body, the measuring arrangement (100) comprising a tubular body (2) having an outer casing and at least one ultrasonic sensor (1) for emitting ultrasonic waves into the interior of the tubular body (2), the ultrasonic sensor (1) being 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 extending normal to the longitudinal axis of the tubular body (2).

Description

[0001] Measurement setup and method for determining ultrasound measurement data

[0002] The invention relates to a measuring arrangement and a method for determining ultrasound measurement data from the interior of a tubular body according to claims 1 and 17, and a method for online determination of the flow direction of a material moving in a tubular body according to claim 18.

[0003] Conveyors with a conveying element, for example a screw conveyor that rotates inside a tubular body, and single-screw and multi-screw extruders for processing and melting polymeric materials are well known in a wide variety of designs.

[0004] Devices comprising a combination of a container, a cutting compactor or preconditioning unit (PCU), and an attached extruder for the pretreatment and processing of polymer waste, in particular various thermoplastic materials, are also well known. Such combination devices have been known for a long time, for example from EP 2 558 263 or EP 2689908.

[0005] All sealing threads housed within a screw housing, and to a lesser extent their housings, are subject to wear, even with the best armor plating. In addition, particularly with screws conveying materials containing abrasive components, such as more or less contaminated, predominantly thermoplastic, recycled plastics, deposits form on both the screw base and the screw housing, in addition to wear. In screws conveying against an extruder head, the aforementioned wear and deposits result in the conveying action required for proper extrusion of the material before the extruder head no longer being reliably established, as the material slips back uncontrollably in the circumferential gaps between the screw and the housing caused by wear and deposits.

[0006] The aforementioned effects are particularly problematic with sealing threads arranged as described above. A loss of conveying efficiency due to wear or deposits in the sealing thread area, which can occur gradually or, in special cases, abruptly, manifests itself through contamination of the material fed into the processing line. This contaminates the final product, typically the granules obtained from the extruder head. This leads to complaints from the end processors of the granules. Contaminated granules not only lose value, but may also necessitate a second thermal filtration process for weeks of granule production. This second heat treatment wastes energy and damages the molecular chains of the plastic material.

[0007] To avoid these difficulties, the sealing threads would need to be removed at regular intervals and both the housing and the screw inspected for wear. However, this work is rarely carried out because it is time-consuming and requires skilled personnel. Wear in the sealing screw area can occur both on the screw itself—not only in terms of the outer diameter of the screw flights but also in terms of the core diameter of the sealing elements—and on the cylindrical screw housing. Furthermore, wear does not always occur continuously and therefore predictably, but can also be abrupt and sudden if the material is sufficiently contaminated.

[0008] The screw seal prevents material from entering the area between the screw and the gearbox. This seal separates the melt / dust from the atmosphere, preventing material flashover. Under certain circumstances, the seal may be insufficient, allowing melt to be forced through the seal in the opposite direction. This can lead to problems such as wear, deposits, unfavorable pressure conditions, loss of conveying efficiency, high moisture ingress, cracking, etc.

[0009] It is also known that information about the material moving inside pipes or similar structures can be obtained by introducing ultrasound. However, this method is currently only partially successful and with low accuracy.

[0010] The object of the present invention is therefore to create a simple and reliable measuring arrangement for the online determination of high-quality ultrasound measurement data from the interior of a tubular body or material.

[0011] The invention solves this problem with a measuring arrangement for introducing ultrasound and for determining ultrasound measurement data from the interior of a tubular body, in particular ultrasound measurement data of a material moving in the tubular body according to claim 1.

[0012] According to the invention, the measuring arrangement comprises a tubular body with an outer shell 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 shell of the tubular body at a coupling angle α of 1° < α < 89°, measured between the longitudinal axis of the ultrasonic sensor and a straight line normal to the longitudinal axis of the tubular body.

[0013] In the context of the invention, a "tubular body" is understood to mean any elongated hollow body in which material can move, regardless of its external or internal cross-sectional shape. Such a tubular body may, for example, have a circular, elliptical, rectangular, or square cross-sectional area, and / or have one or more bores for, for example, an extruder or a conveying element. In particular, typical conveyors, extruders, or pipelines, especially those with cylindrical interiors, are suitable as "tubular bodies" in this context, and their external design is irrelevant.

[0014] In this context, an "ultrasonic sensor" is understood to be a unit designed and suitable for emitting ultrasonic waves into the interior of a tubular body, e.g., 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. Accordingly, the ultrasonic sensor can be a unit that, in addition to emitting ultrasonic waves, is also designed and suitable for detecting them.

[0015] By arranging the ultrasonic sensor according to the invention at an input angle α of 1° < α < 89°, it is advantageously achieved that the first reflection of the ultrasonic waves at the opposite inner wall of the tubular body is either absent or at least significantly weaker. This reflection at 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 to the extent permitted by the input voltage range, meaning that the first reflection would overshadow all other reflections. If this first reflection is eliminated or at least attenuated, this limitation is removed, and the ultrasonic sensor signal is improved because it can be amplified to a significantly higher degree.

[0016] Furthermore, by avoiding or attenuating the first reflection, a higher-power ultrasonic sensor can be advantageously used, and by using oblique coupling, a larger area can be scanned, allowing, for example, changes in wear and flow directions of the moving material inside the tubular body to be identified more accurately.

[0017] With a measuring arrangement according to the invention, it is thus possible to support the monitoring online during the operation of, for example, a conveyor or extruder, of parameters of both the material moving or conveyed in the tubular body and 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 pipe or screw section conveying, for example, a plasticized material, in particular plastic.

[0018] It is also advantageous to be able to determine at any time, e.g. with sealing elements, whether sufficient conveying effect is present, which can be achieved, for example, by measuring the wear of the screw or, if necessary, its screw housing, by measuring the free conveying cross-section, i.e., a measurement of the free channel width and the free channel height, as well as the conveying direction (flow vector), and this can also be done during ongoing production.

[0019] With a measuring arrangement according to the invention or with a method described below, a wide variety of ultrasonic measurements can advantageously be carried out, providing information about the material transported inside the tubular body, as well as about the tubular body itself or components such as screws within the tubular body. For example, geometry- or material-induced effects can be investigated. By measuring the flow direction, it is possible, for instance, to determine whether the flow is from the clean side to the dirty side. If the velocity vector decreases or reverses completely (flow reversal is detected), this can be identified and addressed as an error. The measurement and detection of gas bubbles and / or particles in the polymer melt also becomes possible. In melt-carrying extruder zones, particles or gas bubbles in the melt can be detected and measured.It can detect both the direction of the particle flow or gas bubble flow, as well as the basic presence of bubbles or particles.

[0020] Further advantageous embodiments of a measuring arrangement according to the invention for determining ultrasound measurement data from the interior of a tubular body are described in the dependent claims.

[0021] 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 shell of the tubular body at a coupling angle a of 2° to 70° (2° < a < 70°), especially at a coupling angle a of 6° to 25° (6° < a < 25°).

[0022] According to an embodiment of a measuring arrangement according to the invention, which ensures a further improvement of the ultrasonic sensor signal, the distance of the ultrasonic sensor to an incident radiation surface and / or projection surface at the transition of the outer shell of the tubular body to the interior of the tubular body, which depends on the coupling angle α and the ultrasonic frequency, can be 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 not linear, the intensity can fluctuate, and indications can be incorrectly displayed in their amplitude or completely suppressed, so that it is advantageous to measure outside this area.

[0023] According to a particularly advantageous embodiment of a measuring arrangement according to the invention, the distance Ds, measured from the center of the ultrasonic sensor normal to its radiating surface and / or projection surface, which has a length, in particular a principal axis length, b at the transition of the outer shell of the tubular body to the interior of the tubular body, can be given by:

[0024]

[0025] where the divergence angle 0 is given by the formula:

[0026]

[0027] where k = 0.56 is an experimental constant, A is the ultrasonic wavelength and D is the width and / or diameter of the ultrasonic sensor.

[0028] Such a design of a measuring arrangement according to the invention is particularly suitable for extruders of all types and sizes.

[0029] 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 the main axis length, b of the incident area and / or projection area to the distance Ds of the ultrasonic sensor is in a range of 0.001 to 1, in particular from 0.01 to 0.95, preferably from 0.016 to 0.9.

[0030] According to an embodiment 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 such that an intensity of the emitted ultrasonic waves of 50% can be achieved in a divergence angle range of 0=3.5° to 0=40°, in particular at a divergence angle of about 0=10°.

[0031] According to an embodiment of a measuring arrangement according to the invention, which ensures a further improvement of the signal of the ultrasonic sensor - especially when used to investigate polymer melts as material moving in a tubular body - it can be provided that the ultrasonic sensor has a frequency of 1 MHz to 10 MHz, in particular of 4 MHz.

[0032] A measuring arrangement according to the invention can be designed to be particularly compact if the ultrasonic sensor is configured not only to emit but also to detect ultrasonic waves reflected from the material or the interior of the tubular body. In this way, the measuring arrangement advantageously requires only a combined transmitter / receiver as the ultrasonic sensor, which is designed and suitable for both emitting and receiving reflected ultrasonic waves. Advantageously, a piezoelectric element or piezoelectric transducer can be provided as the ultrasonic sensor, functioning simultaneously as a transmitter and as a detector for the reflected ultrasonic waves from the interior of the tubular body.According to an embodiment of a measuring arrangement according to the invention, which manages with particularly simple components, the measuring arrangement may include 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 shell of the tubular body at a coupling 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 perpendicular to the longitudinal axis of the tubular body.

[0033] According to an embodiment of a measuring arrangement according to the invention, which can be used for a particularly wide variety of measurements, it can be provided that the measuring arrangement comprises, in addition to the first ultrasonic sensor, at least a second or further ultrasonic sensor for emitting ultrasonic waves into the interior of the tubular body,

[0034] wherein the further ultrasonic sensor is arranged in and / or on the outer shell of the tubular body at a coupling angle a of 1° < a < 89°, in particular at a coupling angle a of 2° to 70°, preferably at a coupling angle a of 6° to 25°, measured between the longitudinal axis of the further ultrasonic sensor and a straight line perpendicular to the longitudinal axis of the tubular body in the outer shell of the tubular body,

[0035] wherein the further ultrasonic sensor is arranged in a mirrored and / or parallel arrangement to the first ultrasonic sensor in and / or on the outer shell of the tubular body, and wherein in particular it is provided that the further ultrasonic sensor is also designed to detect reflected ultrasonic waves from the interior of the tubular body.

[0036] In such a configuration, the receiving angle of each ultrasonic sensor is advantageously chosen to be negative relative to the coupling angle of each ultrasonic sensor. In this context, "mirrored" means that the two ultrasonic sensors are positioned opposite each other at the same angle along the longitudinal axis of the tubular body, while "parallel" means that the two ultrasonic sensors are arranged side by side, radiating at the same coupling angle.

[0037] According to an advantageous embodiment 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 screw conveyor.

[0038] According to an advantageous embodiment of a measuring arrangement according to the invention, which is particularly suitable for use in the processing and melting of polymeric materials, the tubular body can be an extruder for processing and melting polymeric materials, comprising at least one screw rotatable within the tubular body and having a web rotating in a spiral shape around a core. The extruder includes a feed section for introducing the material to be processed into the extruder and a downstream extrusion section for melting the material. Advantageously, the extruder includes at least one extruder seal, e.g., a mating thread, with the measuring arrangement being located in the region of the at least one extruder seal.The arrangement of the measuring device in the area of ​​an extruder seal advantageously enables a particularly simple online check of the extruder seal for leaks.

[0039] According to an advantageous embodiment of a measuring arrangement according to the invention, the outer shell of the tubular body may comprise steel, and in particular consist of steel. Due to the significant density differences between steel and, for example, polymer as the material moving within the tubular body, the following special feature arises: The ultrasound coupled obliquely into the steel outer shell of the tubular body is refracted towards the orthogonal direction of the longitudinal axis of the tubular body or of a screw axis, if such a screw is present. This allows transit-time measurements to be performed in the screw channel, and the signals can be amplified much more strongly than with coupling at an angle α of 0°.

[0040] 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 located 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 under pressure is measured, and further parameters can be determined or controlled from this.For example, by measuring the flow direction in backwashable filters, it can be determined whether and how well the backwashing is working.

[0041] In an embodiment that is particularly advantageous for the treatment of polymers, a measuring arrangement or one of the ultrasonic sensors is arranged near an extruder seal between the inlet and outlet channels of a melt filter in the extruder, where a return thread in this area prevents the overflow by reclaiming material.

[0042] In a further advantageous embodiment, a measuring arrangement or one of the ultrasonic sensors is arranged in the extruder at the material feed zone downstream of the gearbox, wherein the screw seal installed there ensures that neither plastic material nor moisture and dust can block the gearing or cause corrosion through constant retraction.

[0043] In a further advantageous embodiment, a measuring arrangement or one of the ultrasonic sensors is positioned on threaded shaft seals of a melt pump that uses melt material specifically for lubricating the shaft within the threaded shaft seal. The function of the shaft seal is to guide the shaft floating on the melt within it, without excessive use or loss of plastic material, and to seal the housing to the outside. To ensure this in a controlled manner, the shaft seals are designed according to the viscosity of the pumped medium and, if necessary, partially cooled to create a seal through the hardened plastic film. However, the seals are limited by the suction pressure and the viscosity of the pumped medium.Inevitable wear and tear, caused by contamination or cracking during the conveying of recycled material, leads to leaks. This results in insufficient suction or cooling for a proper seal, leading to uncontrolled loss of plastic material. Online monitoring with the measuring arrangement according to the invention can help detect these leaks and initiate targeted countermeasures. Furthermore, the invention aims to provide a method for easily obtaining reliable, high-quality ultrasonic measurement data from the material moving inside a tubular body during operation of, for example, a conveyor or extruder.

[0044] The invention solves this problem by providing and using at least one measuring arrangement for determining ultrasonic measurement data from the interior of a tubular body, in particular ultrasonic measurement data of a material moving within the tubular body, and in particular a measuring arrangement according to the invention as described above. The measuring arrangement comprises a tubular body with an outer shell 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 shell of the tubular body at a coupling angle α of 1° < α < 89°, measured between the longitudinal axis of the ultrasonic sensor and a straight line perpendicular to the longitudinal axis of the tubular body. The oblique coupling avoids or...This weakens the first reflection, and a higher-powered ultrasonic sensor can be used advantageously.

[0045] The further object of the invention is to provide a method by which it is possible to determine the flow direction of a material moving in a tubular body in a simple and reliable manner online during the operation of, for example, a conveyor or extruder.

[0046] The invention solves this problem with a method for online determination of the flow direction of a material moving, in particular conveyed, in a tubular body, wherein at least one measuring 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 measuring arrangement comprises a tubular body with an outer shell 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 shell of the tubular body at a coupling angle α of 1° < α < 89°, measured between the longitudinal axis of the ultrasonic sensor and a straight line perpendicular to the longitudinal axis of the tubular body, in particular by means of or by means ofusing one of the previously described measuring arrangements according to the invention. The method according to the invention comprises the following steps:

[0047] A highly compressed, molten, slurry-like or liquid material is moved or conveyed inside the tubular body, for example a conveyor, extruder or pipeline.

[0048] the emission of ultrasound waves into the moving or conveyed material or into the interior of the tubular body,

[0049] a repeated recording of the ultrasound transit times of ultrasound waves reflected from the interior of the tubular body by inhomogeneities in the material and / or inhomogeneities of the material over a predetermined measurement period during movement or conveying,

[0050] a determination of the flow direction of the material relative to the ultrasonic sensor of the measuring arrangement based on the determined transit time shift of at least one respective inhomogeneity over several repeated measurements and the known geometric arrangement of the ultrasonic sensor relative to the tubular body.

[0051] In the context of the invention, "inhomogeneities" are understood to mean any detectable deviations within the material or the material itself. This includes both inhomogeneities occurring in the material moved or conveyed in the tubular body, for example, a melt, such as particles, gas bubbles, water, or contaminants, and inhomogeneities affecting the material, for example, the melt itself, such as material components exhibiting density, pressure, and / or temperature differences compared to the rest of the material.

[0052] In the context of the invention, a "transit time shift" means that the transit time of ultrasonic waves reflected from, for example, a particle towards the ultrasonic sensor or ultrasonic detector shifts over several measurements depending on the direction of movement of the particle, i.e., it shortens or lengthens.

[0053] Determining the actual flow direction of the material offers significant advantages in establishing confidence in the tightness of a tubular body or the effectiveness of any seal arranged within the tubular body. Compared to known measurements of the tightness of screw seals via differential pressure, determining the flow direction using ultrasound has the advantage of being independent of the calibration of the sensors used. Furthermore, the measurement of the flow direction is not subject to long-term drift or wear. Further advantageous embodiments of the method according to the invention are described in the dependent claims.

[0054] According to an advantageous embodiment of a method according to the invention, the flow direction of the material can be determined based on the slopes of the reflections of the ultrasound waves reflected at at least one inhomogeneity, or based on the reflections of the ultrasound waves reflected at at least one inhomogeneity and the resulting slope plotted against the ultrasound transit time over the measurement period. Using multiple reflections is particularly simple and reliable for determining the flow direction, as this ensures higher sensitivity. The slope of the curves increases with each reflection because the differences in transit times due to, for example, pressure and thus density differences in the material are multiplied.

[0055] The evaluation based on the determined transit time shift can be carried out particularly easily if, in order to determine the flow direction of the material, the ultrasonic transit time of the ultrasonic waves reflected at at least one inhomogeneity is plotted over the measurement period as a transit time profile.

[0056] In this context, further simplification of the evaluation and, in particular, a particularly rapid, automated evaluation can be made possible if the runtime profile is available as an image file, whereby it is specifically intended that image processing algorithms are used to evaluate the slope of the reflections of the ultrasound waves reflected at at least one respective inhomogeneity.

[0057] When the ultrasonic sensor is oriented against the normal flow direction, a positive slope can be interpreted as an upstream flow (desired state) and a negative slope as an outstream flow (malfunction). The opposite can occur when the ultrasonic sensor is oriented in the direction of flow.

[0058] According to an advantageous embodiment of the inventive 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 undergoing processing, in particular extrusion, is conveyed as the 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.

[0059] A method according to the invention can be carried out particularly reliably and in a time-saving manner if a measuring arrangement designed according to the invention is used.

[0060] According to an advantageous embodiment of a method according to the invention, which is particularly suitable for use in conveyors of any kind, it can be provided that the material is conveyed inside a tubular body designed as a conveyor with a conveying element, in particular with a screw conveyor.

[0061] According to an advantageous embodiment of a method according to the invention, 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 by means of at least one screw rotatable in the tubular body with a web rotating in a spiral shape around a core, wherein the extruder comprises a feed area for introducing the material to be processed into the extruder and a further downstream extrusion area, in particular with at least one extruder seal for melting the material, and wherein the measuring arrangement is arranged in the area of ​​the at least one extruder seal.

[0062] The invention further relates to a method for processing, in particular for recycling, a polymer, wherein the polymer is melted and a method according to the invention is used for online determination of the flow direction of the polymer.

[0063] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0064] The invention is schematically illustrated below with reference to particularly advantageous, but not limiting, embodiments in the drawings and is described by way of example with reference to the drawings. The following schematically illustrates:

[0065] Fig. 1 shows an embodiment of a known arrangement of an ultrasonic sensor on a tubular body,

[0066] Fig. 2 shows a schematic view of an embodiment of a measuring arrangement according to the invention for determining ultrasonic measurement data from the interior of a tubular body,

[0067] Fig. 3 shows an example of the pulse voltage plotted against the transit time in the embodiment from Fig. 1.

[0068] Fig. 4 shows an example of the pulse voltage after subtraction of the first reflection at the inner wall of the tubular body plotted against the transit time in the embodiment from Fig. 1.

[0069] Fig. 5 shows a schematic view of a further embodiment of a measuring arrangement according to the invention,

[0070] Fig. 6 shows a schematic view of a further embodiment of a measuring arrangement according to the invention,

[0071] Fig. 7 shows a side view of an embodiment of a measuring arrangement according to the invention.

[0072] Fig. 8 shows another side view of an embodiment of a measuring arrangement according to the invention,

[0073] Fig. 9 shows a schematic representation of a measuring arrangement according to the invention with coupling angle a and divergence angle 0, distance Ds of the ultrasonic sensor from the inner wall of the tubular body,

[0074] Fig. 10 shows a schematic representation of the relationship between ultrasound intensity and divergence angle 0, as well as the geometry of the ultrasound sensor.

[0075] Fig. 11 shows a representation of the relationship of the coupling angle in steel a st and the angle of refraction in polymer melt a SC h at temperature- and pressure-dependent sound velocities in the melt,

[0076] Fig. 12 shows a first schematic representation of the relationship between coupling angle a, distance Ds and the incident radiation surface or projection surface with axis length b,

[0077] Fig. 13 shows a second schematic representation of the relationship between coupling angle a, distance Ds and the incident radiation surface or projection surface with axis length b,

[0078] Fig. 14 shows the relationship between the coupling angle in steel a S t and refraction angle in polymer melt a SC h, Fig. 15 a representation of the relationship between coupling angle in steel a S t and refraction angle in polymer melt a SC h at different temperature-dependent sound velocities in steel,

[0079] Fig. 16a shows a schematic representation of the derived flow direction of the material in a tubular body,

[0080] Fig. 16b shows a schematic representation of the pressure applied against the channel position in the tubular body from Fig. 16a.

[0081] Fig. 16c shows a schematic representation of the speed of sound plotted against the channel position in the tubular body from Fig. 16a.

[0082] Fig. 17 shows an exemplary embodiment of a transit-time profile for deriving the flow direction. Fig. 18a shows a schematic representation of the path of the ultrasound when observing a particle with a flow direction from left to right.

[0083] Fig. 18b shows a schematic representation of the path of ultrasound when observing a particle with a flow direction from right to left.

[0084] Fig. 19a shows a schematic representation of the ultrasonic path between the ultrasonic sensor and a particle with a flow direction from left to right.

[0085] Fig. 19b shows a schematic representation of the ultrasonic path between the ultrasonic sensor and a particle with a flow direction from right to left.

[0086] Fig. 20a shows a schematic representation of the ultrasound transit time plotted against the measurement number for the example from Fig. 18a and 19a.

[0087] Fig. 20b shows a schematic representation of the ultrasound transit time plotted against the measurement number for the example from Fig. 18b and 19b,

[0088] Fig. 21a shows a runtime profile in the form of an image file for the example from Figs. 18a and 19a,

[0089] Fig. 21b shows a runtime profile in the form of an image file for the example from Fig. 18b and 19b,

[0090] Fig. 22 shows a schematic representation of the evaluation of the flow direction based on the transit time profiles from Fig. 21a and 21b.

[0091] Fig. 23a, b and c shows the arrangement of one or more ultrasonic sensors.

[0092] Fig. 1 shows an embodiment of a known arrangement of an ultrasonic sensor or transmitter 1 on a tubular body 2. In this embodiment, the tubular body is an extruder with a cylindrical outer shell, inside which an extruder screw rotates and conveys a polymer melt 3. The cylindrical wall of the tubular body 2 is made of steel in this embodiment. As can be seen in Fig. 1, ultrasonic measurements on extruders and plasticizing units are implemented by mounting the ultrasonic sensor 1 orthogonally to the cylinder or screw axis. In this known arrangement, the ultrasonic signal is thus coupled orthogonally into the cylinder wall and subsequently into the polymer melt 3.

[0093] A disadvantage of this arrangement of the ultrasonic sensor 1 on the tubular body 2 is that the amplification is limited by the strong reflection from the inner wall of the cylinder. This is shown schematically in Fig. 3. Fig. 3 shows the pulse voltage V plotted against the transit time dt in the voltage input range ADC. The ultrasonic signal must only be amplified to the extent that the reflection remains within the voltage input range ADC. After subtracting the first reflection from the inner wall of the tubular body 2, or the cylinder wall reflection, only a very small signal from the melt channel or the polymer melt 3 remains, in the range of 3–5% of the cylinder wall amplitude.

[0094] If this first reflection is eliminated, this limitation is removed and the sensor signal improves because it can be amplified significantly more. In a measuring arrangement 100 according to the invention, this "elimination" or reduction of the first reflection at the inner cylinder wall is achieved by selecting a coupling angle α – measured between the longitudinal axis of the ultrasonic sensor 1 and a straight line perpendicular to the longitudinal axis of the tubular body 2 – of 1° < α < 89° and by arranging the ultrasonic sensor 1 obliquely in or on the outer surface of the tubular body 2. Ideally, the coupling angle α lies in a range of 2° to 70° (2° < α < 70°), and optimally in a range of 6° to 25° (6° < α < 25°). This is illustrated in Fig. 2, where the coupling of the ultrasonic signal from the ultrasonic sensor 1 into the cylinder wall of the tubular body 2 made of steel is shown specifically at a coupling angle α. st from 45°.

[0095] The oblique coupling has the advantage that the initial, very intense sound wave reflection is not reflected directly back to the sensor. This allows for the use of higher ultrasound energies, which would normally overload the ultrasound detector or the combined ultrasound transmitter / detector. At the same time, the reflections from the cochlea can still be observed.

[0096] To achieve this, angles of, for example, 1° < a < 89° are suitable, angles of 2° < a < 70° are favorable, and angles of 6° < a < 25° are most appropriate. These angles are derived from various tests on the temperature and pressure stability of the refractive index during the transition into the melt.

[0097] Furthermore, the distance Ds of the ultrasonic sensor 1 from the inner wall of the extruder is important, as this distance defines the sound transmission area on the interface as a function of the angle α. Ideally, this distance should be larger than the blind zone of the ultrasonic sensor 1 (> 17 mm) and smaller than the available material thickness of the extruder. The further the ultrasonic sensor 1 is from the inner wall of the extruder, the larger the sound transmission area b becomes, assuming a constant coupling angle α but a divergence angle of 0. The larger this area becomes, the less energy can be coupled into the melt zone of the extruder.

[0098] Through geometric relationships, a formula was developed for the above description which ensures general validity across all extruder sizes (see Fig. 9):

[0099]

[0100] where the divergence angle 0 is given by the formula:

[0101]

[0102] The ratio b / Ds thus yields a range of 0.001-1, in particular 0.01-0.95, or particularly advantageously 0.016-0.90:

[0103] 0.9

[0104]

[0105] where k = 0.56 is an experimental constant that makes the divergence angle large enough that approximately 50% of the emitted ultrasound energy lies within the cone, and

[0106] where A is the ultrasonic wavelength (depending on the excitation frequency 1 - 10 MHz), and where D is the sensor width.

[0107] An advantage of an input angle of 1° < a < 89° is the absence, or at least a significantly weaker, first reflection from the inner wall of the cylinder. This reflection is very strong when the input angle is 90° to the longitudinal axis of the tubular body 2 (a = 0°), and the ultrasonic signal can only be amplified to the extent permitted by the input voltage range. The first reflection would overshadow or mask all other reflections. Eliminating this first reflection removes this limitation, and the ultrasonic sensor signal is improved because it can be amplified to a much higher degree. By avoiding or attenuating the first reflection, a higher-power ultrasonic sensor 1 can also be used.

[0108] Within a coupling angle range of 6° to 25°, the refraction angle behaves linearly (see Fig. 14), particularly with changes in pressure and temperature (see Fig. 11 and Fig. 15). At lower angles < 6°, there is hardly any advantage with regard to first reflection (see Fig. 12 and Fig. 13). At higher angles > 25°, the ultrasonic energy is again widely distributed over the large cross-sectional area of ​​the sound cone, and the percentage of reflected sound increases. This results in more inhomogeneities within the sound cone, but a correspondingly lower reflection intensity must be taken into account, which can make detection more difficult. Physically speaking, the maximum effect occurs at total internal reflection.

[0109] Additionally, the oblique coupling angle allows for the scanning of a larger area, enabling, for example, more precise identification of changes in extruder wear (see Figs. 12 and 13). The higher the coupling angle, the wider the area under investigation, or rather, the more information the reflected measurement signal contains. The automated evaluation can thus potentially detect more inhomogeneities, thereby increasing the accuracy of the result. With a higher coupling angle, the proportion of detected periodic reflections decreases, while the sound path to the measurement point increases, both of which have a positive effect on signal interpretation. Both effects increase the time interval between detected reflections and thus the time in which other information can be acquired.

[0110] Another advantage, which is particularly evident in the steel / plastic pairing, is that the large differences between steel and plastic lead to very small angles of refraction, and the measurement results (e.g. gap width) are therefore comparable to classical coupling.

[0111] 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 occurs: The ultrasound coupled obliquely into the cylindrical steel is refracted at an angle α SC The direction h is broken towards the orthogonal direction of the worm's axis. This allows transit-time measurements to be taken in the worm's channel and the ultrasound signals to be amplified much more strongly than with classical orthogonal coupling.

[0112] The following table provides an overview of sound velocities and refraction angles a SC h at different polymer types, pressures and temperatures:

[0113] S cha 11 g esc hwindig ke it:

[0114]

[0115] Average PP,PE,PET: 6.7°

[0116] The relationship between the coupling angle in steel (45° in the example) and the refraction angle in the polymer is given by the following relationship:

[0117]

[0118] Fig. 15 shows the relationship between the angles a st and a SC h at various temperature-dependent sound velocities in steel. It turns out that the deviations are negligible. Fig. 15 shows the ultrasonic velocity in steel assumed to be at room temperature, average temperature, and up to a maximum of 350 °C – represented by the three curves. In Fig. 15, the x-axis represents the coupling angle a. st plotted. The corresponding angle of refraction α is found on the y-axis. SCh of the sound wave in the melt after it has been refracted at the interface. The sound wave is refracted from the denser medium to the less dense medium towards the normal, which is recognizable by the different axis scaling.

[0119] Fig. 11 shows the relationship between angles at temperature- and pressure-dependent sound velocities in the melt, where the p- and T-ranges correspond to typical plastics recycling plants. It is evident that the deviations increase, but are acceptable within the defined measurement range of 6° to 25°. For this diagram, it is assumed that the steel temperature remains constant, but the melt temperature and / or pressure change. Furthermore, the curves are averaged over different polymers; the x- and y-axes are to be interpreted as in Fig. 15.

[0120] Fig. 5 shows a schematic view of a further embodiment of a measuring arrangement 100 according to the invention. In Fig. 5, the integration of the ultrasonic sensor 1 into the outer shell of the tubular body 2 is achieved by providing a milled or turned inclined surface in the outer shell.

[0121] Fig. 6 shows a schematic view of a further embodiment of a measuring arrangement 100 according to the invention. In Fig. 6, the integration of the ultrasonic sensor 1 into the outer shell of the tubular body 2 is achieved by providing a blind hole and a thread for fastening the ultrasonic sensor 1 in the outer shell.

[0122] Figures 7 and 8 show the specific embodiment of a measuring arrangement 100 according to the invention on an extruder for processing and melting polymeric materials with a screw rotating in a tubular body 2 and a web rotating in a spiral shape around a core. In Figures 7 and 8, the housing of the extruder is shown in a cutaway view, while the extruder with screw is shown in a side view within the cutaway housing. In the exemplary embodiments, the extruder has a feed section (not shown here) for introducing the material to be processed into the extruder and an extrusion section located further downstream for melting the material. An extruder seal in the form of a return conveying or damming element is also provided there, and the measuring arrangement 100 is arranged in the area of ​​the extruder seal of the extruder. The sealing thread can be identified by the fact that it is oriented in the opposite direction to the thread of the rest of the extruder.The ultrasonic sensor 1 does not need to be attached to the point shown in Fig.

[0123] The ultrasonic sensor 1 does not need to be arranged in the position shown in Figures 7 or 8, but can advantageously also be installed in the area close to the sealing thread. As described below, a second or further ultrasonic sensor can also be installed in this area. The integration of the ultrasonic sensor 1 in Figures 7 and 8 corresponds to the embodiments shown in Figures 5 and 6, respectively.

[0124] Examples of an optimized power range or intensity of the ultrasonic sensor 1 used for a combination of steel and polymer melt 3 are 0.001 W / cm². 2 - 2 W / cm 2 A lower power output prevents the detection of inhomogeneities in the polymer melt. 3.2 W / cm² 2This is already within the range of high-power sound, and higher power levels would damage the polymer. An example of an optimized frequency range for the ultrasonic sensor 1 used for a combination of steel and polymer melt 3 is 1 MHz - 10 MHz.

[0125] In the illustrated embodiments of a measuring arrangement 100 according to the invention, the distance of the ultrasonic sensor 1 to the "measuring point" in the polymer melt 3 is greater than the near-field length of the ultrasonic sensor 1, i.e., greater than 10 mm, for example, 17 mm. The distance of the ultrasonic sensor 1 to an incident radiation surface, which has a length (in this embodiment, a principal axis length) b of 0.6 to 35 mm at the transition from the outer shell of the tubular body 2 to the interior of the tubular body or to the polymer melt 3, at an incident angle α of 6° to 25°, is therefore greater than the near-field length of the ultrasonic sensor 1, in particular greater than 10 mm, preferably 17 mm.

[0126] The area of ​​sound focusing, characterized by interference with maxima and minima of sound pressure, is called the near field. The end of the near field in the direction of sound propagation is defined by the last maximum of the sound pressure amplitude distribution. A natural focusing of the sound field is present in the near field. The distance at which the near field transitions into the far field is the near field length. It depends on the transducer size and the wavelength in the test piece.

[0127] Furthermore, in the exemplary embodiments, the ultrasonic sensor 1 is designed, or its diameter D and its frequency f are selected, such that an intensity I of the emitted ultrasonic waves of 50% can be achieved in a divergence angle range of 0=3.5° to 0=40° (3.5° < 0 < 40°, ideally at a divergence angle of approximately or exactly 10°).

[0128] The divergence angle 0 is calculated according to the following relationship:

[0129]

[0130] where

[0131] K... constant

[0132] ... wavelength (X=c / f)

[0133] c... speed of sound

[0134] f....Frequency As can be seen in Fig. 10, the ultrasound intensity in the sound cone emitted by the ultrasound sensor 1 is not constant. It decreases towards the outside. Measurements should be avoided within the near field if possible, as strong intensity fluctuations occur there.

[0135] The following are some calculation examples for the optimized divergence angles 0 for a combination of a tubular body 2 made of steel and polymer melt 3 inside the tubular body 2. The ultrasonic sensor 1 is designed as a piezoelectric transducer.

[0136] o D = 10 mm of = 4 MHz

[0137] Speeds of sound

[0138] o CStahl = 5880 m / s

[0139] o CPolymer = 1000 m / s

[0140] calculations

[0141] • Wavelength:

[0142] o 0.00147 m

[0143]

[0144] • Diverge

[0145] O

[0146]

[0147] « • -1 / 1.08 * 0.80147\ o

[0148] c Ö 1 Q S<Ä

[0149] ,, G = sin 1 - — — I = 9.13

[0150] \ 10 » io-® /

[0151] o 4.7

[0152]

[0153] • Near-field length:

[0154]

[0155] The angles given here refer to the coupling angle α. S t into the steel. During the transition to the melt, a change in angle 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, wherein the ultrasonic sensor 1 simultaneously acts as a detector for the reflected ultrasonic waves from the interior of the tubular body 2.

[0156] The measuring arrangement 100 according to the invention can also include 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 shell of the tubular body 2 at an angle α of < 89° between the longitudinal axis of the ultrasonic detector and a straight line normal to the longitudinal axis of the tubular body.

[0157] One, in particular a single, ultrasonic sensor 1, which simultaneously functions as a detector, or one, in particular a single, ultrasonic sensor 1 and one, in particular a single, ultrasonic detector are in principle sufficient for the above-mentioned measurements such as flow direction measurements.

[0158] In a measuring arrangement 100 according to the invention, not only a single ultrasonic sensor 1 (Fig. 23a) but also two or more ultrasonic sensors 1 can be provided, particularly when more complex measurements are to be performed: For example, two or more ultrasonic sensors 1 can be used for advantageous measurements or conclusions regarding wear, screw deflection or screw oscillation, but also for flow direction detection and estimation, including estimation of the swirl of the melt in the screw flight. The second ultrasonic sensor 1 can either be arranged mirrored along a normal to the longitudinal axis, i.e., opposite each other at the same angle (Fig. 23b), or arranged parallel at the same angle directly next to the first ultrasonic sensor 1 along the longitudinal axis, i.e., side by side and emitting at the same coupling angle (Fig. 23c).

[0159] The distance between the ultrasonic sensors along the longitudinal axis of the tubular body is 0–0.2 L / D in parallel operation, whereby the ultrasonic sensors should generally be positioned as close together as possible. The distance between the sensors along the longitudinal axis of the tubular body is 0–2 L / D, and in particular 0–1 L / D, in mirrored operation.

[0160] As mentioned previously, with a measuring arrangement 100 according to the invention, including an ultrasonic sensor 1, it is possible to quickly and easily obtain high-quality ultrasonic signals and subsequently perform a wide variety of measurements in a tubular body 2, such as an extruder with a screw. The ultrasonic sensor 1 is optimally arranged along the screw thread (in the direction of the incline, see Figs. 7 and 8).

[0161] 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 flow direction is from right to left. Three longitudinal positions are marked to better illustrate the ultrasonic velocity intervals. Fig. 16b shows the pressure p in the y-direction. In screw conveyors used in plastics processing, the pressure in the screw channel drops almost linearly from the active (driving) flank to the passive flank. The pressure then rises linearly again across the screw web (from the passive to the active flank) (see Fig. 16b).

[0162] 16b).

[0163] The ultrasonic transit time in polymer melts decreases almost linearly with increasing pressure (ultrasound velocity increases, see Fig. 16c) and increases with increasing melting temperature (ultrasound velocity decreases, see Fig. 16b). Therefore, the pressure profile can be directly inferred from the ultrasonic transit time, particularly accurately assuming that the melt temperature in the channel is relatively constant. Thus, inhomogeneities in polymer melts can be detected using ultrasound. Fig. 16c illustrates the direct relationship between the pressure p in the melt and the ultrasonic velocity c, which is represented on the y-axis. Several velocity regimes can therefore be distinguished in the detected ultrasonic signal; Fig. 17 shows actual data from such a measurement.

[0164] Based on these circumstances, a method according to the invention for online determination of the flow direction of a material moving in a tubular body 2 could be developed, on which a measuring arrangement 100 according to the invention, as described above, for example, is arranged.

[0165] In an embodiment that enables the online determination of the flow direction of a polymer melt 3 moving in a cylindrical extruder, the following process steps are provided, for example:

[0166] Moving or conveying material, such as compressed pieces of material, partially molten, molten, slurry or liquid material, inside the tubular body 2, for example inside an extruder for processing and melting polymeric materials with at least one rotatable screw inside, in the context of recycling a polymer, wherein the polymer is melted and thus moves through the extruder as polymer melt 3,

[0167] Emission of ultrasonic waves into the interior of the extruder or material during the movement or conveying of the polymer melt 3,

[0168] Repeated recording of the transit time of ultrasonic waves reflected from inside the extruder by inhomogeneities in the conveyed polymer melt 3 and / or inhomogeneities of the conveyed polymer melt 3 over a predetermined measurement period during conveying, and

[0169] Determination of the flow direction of the polymer melt 3 relative to the ultrasonic sensor 1 of the measuring arrangement 100 based on the determined transit time shift of at least one respective inhomogeneity over several repeated measurements and the known geometric arrangement of the ultrasonic sensor 1 relative to the extruder.

[0170] The movement of a given inhomogeneity relative to the ultrasonic sensor 1 is thus tracked by means of the corresponding ultrasonic transit times over a predetermined measurement period or observation period, as shown schematically in Fig. 18a, 18b, 19a and 19b.

[0171] Such "inhomogeneities" can be inhomogeneities that occur as foreign bodies within a more or less homogeneous polymer melt 3, for example, particles, gas bubbles, water, or contaminants. However, "inhomogeneities" can also be inhomogeneities within the otherwise homogeneous polymer melt 3, such as melt components that exhibit pressure and / or temperature differences compared to the rest of the processed polymer melt 3.

[0172] Fig. 18a shows the path of the ultrasound when observing a particle moving past the ultrasound sensor 1 inside the tubular body 2 or the extruder with flow direction FR from left L to right R. Fig. 19a schematically shows the ultrasound path between the ultrasound sensor 1 and the particle moving with flow direction FR from left L to right R. M , n This indicates the sound path during a measurement n. The sound path LM , n The transit time increases from the first measurement (n=1) to the third measurement (n=3). This increase is also shown by the arrow in Fig. 20a, where the ultrasonic transit time dt is plotted against the measurement number. Fig. 18b shows the path of the ultrasound when observing a particle moving past the ultrasonic sensor 1 inside the tubular body 2 or the extruder with flow direction FR from right R to left L. Fig. 19b schematically shows the ultrasonic path between the ultrasonic sensor 1 and the particle during movement with flow direction FR from right R to left L. M , n This again indicates the sound path during a measurement n. The sound path L M , n The transit time decreases from the first measurement (n=1) to the third measurement (n=3). This decrease is also shown by the arrow in Fig. 20b, where the ultrasonic transit time dt is plotted against the measurement number.

[0173] Tests on the seal revealed that the flow direction FR of the material in the screw cross-section can be determined particularly reliably by examining the slopes of the reflections of the ultrasonic waves repeatedly reflected at a given inhomogeneity. This is done by plotting the ultrasonic transit time dt against the measurement duration MD. Figures 21a and 21b show such a representation in the form of a transit-time profile, prepared as an image file, for the examples from Figures 18a and 18b. The individual lines or curves in Figures 21a and 21b represent individual inhomogeneities, and the trend of the ultrasonic transit time dt for a selected inhomogeneity is symbolically indicated by an arrow. If such a transit-time profile is available as an image file, various well-known image processing algorithms, such as 2D FFT, can be used to evaluate the slope.

[0174] Ideally, it is known whether the measurement is carried out in a pressure-consuming area (negative pressure gradient Ip) or in a pressure-building area (positive pressure gradient hp), or in which area the ultrasonic sensor 1 is arranged in the tubular body 2.

[0175] Fig. 17 shows actual measurement data from an ultrasonic measurement. The x-axis represents the measurement duration MD, and the y-axis represents the transit time dt of the detected ultrasonic signals or the transit time of the reflected wave. The plotted slope increases with each reflection because the sound wave travels through the melt twice more per reflection signal. The velocity difference between high and low pressure in the melt thus comes into play again with each reflection.

[0176] Therefore, the use of multiple reflections (see Fig.) is advantageous for the evaluation.

[0177] 17), since a higher sensitivity can be utilized here. The slope of the curves increases with each reflection because the differences in 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 based on the transit time profiles in Figs. 21a and 21b. Depending on the slope, a flow direction FR from left L to right R (descending) or from right R to left L (ascending) is determined.

[0178] Information on the actual flow direction FR of the material offers significant advantages in building confidence in the effectiveness of the seal (constant measurement).

Claims

Patent claims 1. 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 shell 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 shell 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 normal to the longitudinal axis of the tubular body (2).

2. Measuring arrangement (100) according to claim 1, characterized in that the ultrasonic sensor (1) is arranged in and / or on the outer shell of the tubular body (2) at a coupling angle a of 2° to 70°, in particular at a coupling angle a of 6° to 25°.

3. Measuring arrangement (100) according to claim 1 or 2, characterized in that the distance of the ultrasonic sensor (1) to an incident radiation surface and / or projection surface at the transition of the outer shell of the tubular body (2) to the interior of the tubular body (2), which depends 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.

4. Measuring arrangement (100) according to one of the preceding claims, characterized in that the distance Ds, measured from the center of the ultrasonic sensor (1) normal to its radiating surface and / or projection surface, which has a length, in particular a principal axis length, b at the transition of the outer shell of the tubular body (2) to the interior of the tubular body (2), is given by: where the divergence angle 0 is given by the formula: where k = 0.56 is an experimental constant, A is the ultrasonic wavelength and D is the width and / or diameter of the ultrasonic sensor (1).

5. Measuring arrangement (100) according to claim 4, characterized in that the ratio b / Ds of the length, in particular the principal axis length, b of the incident area and / or projection area to the distance Ds of the ultrasonic sensor (1) is in a range of 0.001 to 1, in particular from 0.01 to 0.95, preferably from 0.016 to 0.

9.

6. Measuring arrangement (100) according to one of the preceding claims, characterized in that the at least one ultrasonic sensor (1) is designed such that the diameter and / or the frequency of the at least one ultrasonic sensor (1) is selected such that an intensity of the emitted ultrasonic waves of 50% can be achieved in a divergence angle range of 0=3.5° to 0=40°, in particular at a divergence angle 0=10°.

7. 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.

8. Measuring arrangement (100) according to one of the preceding claims, characterized in that the ultrasonic sensor (1) is designed for the detection of reflected ultrasonic waves from the interior of the tubular body (2) or as an ultrasonic detector.

9. 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 shell of the tubular body (2) at a coupling angle α of 1° < α < 89° measured between the longitudinal axis of the ultrasonic sensor (1) or ultrasonic detector and a straight line normal to the longitudinal axis of the tubular body (2).

10. 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 located in and / or on the outer shell of the tubular body (2) at a coupling angle α of 1° < α < 89°, in particular at a coupling angle α of 2° to 70°, preferably at a coupling angle α of 6° to 25°, measured between the longitudinal axis of the further ultrasonic sensor and a is arranged perpendicular to the longitudinal axis of the tubular body (2), wherein the further ultrasonic sensor is arranged in and / or on the outer shell of the tubular body (2), mirrored and / or parallel to the ultrasonic sensor (1), and wherein it is particularly provided that the further ultrasonic sensor (1) is also designed to detect reflected ultrasonic waves from the interior of the tubular body (2).

11. 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 section of a conveyor or extruder.

12. 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 with at least one screw rotatable in the tubular body (2) having a web rotating in a spiral shape around a core, wherein the extruder comprises a feed area for introducing the material to be processed into the extruder and a further downstream extrusion area for melting the material, wherein the extruder preferably comprises at least one extruder seal and the measuring arrangement is arranged in the area of ​​at least one of the extruder seals.

13. Measuring arrangement (100) according to one of the preceding claims, characterized in that the outer shell of the tubular body (2) comprises steel, in particular is made of steel.

14. Measuring arrangement (100) according to one of the preceding claims, characterized in that the measuring arrangement (100) is designed for determining ultrasonic measurement data of a polymer located in the tubular body (2) undergoing 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.

15. 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 located on or in melt lines, melt guides or melt filters, or in an extruder directly next to an extruder seal or a return feed thread, in particular between the inlet and outlet channel of an extruder. melt filters, or in the material feed zone of an extruder, or directly next to threaded shaft seals in a melt pump.

16. Conveyor or extruder for processing or melting polymer material comprising at least one measuring arrangement (100) according to any one of claims 1 to 15.

17. Method for determining ultrasound measurement data from the interior of a tubular body, in particular ultrasound measurement data of a material moving in a tubular body, wherein at least one measuring arrangement (100) 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 measuring arrangement (100) comprises a tubular body (2) with an outer shell 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 shell of the tubular body (2) at a coupling angle α of 0° < α < 89°, measured between the longitudinal axis of the ultrasonic sensor (1) and a straight line perpendicular to the longitudinal axis of the tubular body (2), in particular a measuring arrangement (100) according to any one of claims 1 to 16, 18. Method for online determination of the flow direction (FR) of a material moving, in particular conveyed, in a tubular body (2), wherein at least one measuring arrangement (100) 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 measuring arrangement (100) comprises a tubular body (2) with an outer shell 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 shell of the tubular body (2) at a coupling angle α of 0° < α < 89°, measured between the longitudinal axis of the ultrasonic sensor (1) and a straight line perpendicular to the longitudinal axis of the tubular body (2), in particular a measuring arrangement (100) according to any one of claims 1 to 16, comprehensively the following steps: emission of ultrasound waves into the material moving inside the tubular body (2), Repeated recording of the ultrasonic transit time (dt) of ultrasonic waves reflected from the interior of the tubular body (2) by inhomogeneities in the material and / or inhomogeneities of the material over a predetermined measurement period (MD), determination of the flow direction (FR) of the material relative to the ultrasonic sensor (1) based on the determined transit time shift of at least one respective inhomogeneity over several repeated measurements and the known geometric arrangement of the ultrasonic sensor (1) relative to the tubular body (2).

19. Method according to claim 18, characterized in that the flow direction (FR) of the material is determined on the basis of reflections of the ultrasound waves reflected at at least one respective inhomogeneity and the resulting slope in a representation of the ultrasound transit time (dt) plotted against the measurement time (MD).

20. Method according to claim 18 or 19, characterized in that, to determine the flow direction (FR) of the material, the ultrasonic transit time (dt) of the ultrasonic waves reflected at at least one respective inhomogeneity is plotted against the measurement duration (MD) as a transit time profile.

21. Method according to claim 20, characterized in that the time-of-flight profile is available as an image file, wherein it is particularly provided that image processing algorithms are used to evaluate the slope of the reflections of the ultrasound waves reflected at at least one respective inhomogeneity.

22. Method according to one of claims 18 to 21, characterized in that the material in the tubular body (2) is a polymer or a polymer melt undergoing processing, in particular extrusion, and the polymer has a dynamic viscosity η of 0 to 500,000 Pa*s, in particular of 50 to 300,000 Pa*s.

23. Method according to one of claims 18 to 22, characterized in that the material is moved or conveyed inside a melt line for molten polymer, is conveyed inside a tubular body (2) designed as a conveyor with a conveying element, in particular with a screw conveyor, and / or inside a tubular body designed as an extruder for processing and melting polymeric materials with at least one in the tubular The body (2) is conveyed by a rotatable screw with a spiral-shaped web (2) surrounding a core, wherein the extruder comprises a feed area for introducing the material to be processed into the extruder and a further downstream extrusion area with at least one extruder seal for melting the material, and wherein the measuring arrangement is arranged in the area of ​​at least one of the extruder seals.

24. A method for processing, in particular for recycling, a polymer, wherein the polymer is melted and the method for online determination of the flow direction of the polymer according to one of claims 18 to 23 is used.

Images