Measuring tube and method for manufacturing a tubular component

Abstract

The invention relates to a measuring tube (1), in particular for use in an ultrasonic measuring device (100), comprising: - a measuring tube body (10) for guiding a medium, wherein the measuring tube body has a connection section (AA), wherein the measuring tube body (10) has a non-angular, in particular round, first (inner) contour (K1) in a cross-section through the connecting section (AA), wherein the measuring tube body (10) has a measuring section (MA), wherein the measuring tube body (10) has an (inner) measuring section circumference (MAU) in the measuring section (MA), wherein the measuring tube body (10) in the measuring section (MA) has at least one planar outer surface (AF), in particular for attaching at least one ultrasonic transducer (20), wherein the measuring tube body (10) has a second (inner) contour (K2) in a cross-section intersecting the planar outer surface (AF), wherein the measuring tube body (10) has a transition section (UA) which is located between measuring section (MA) and connecting section (AA), wherein the measuring tube body (10) has a third (inner) contour (K3) in a cross-section of the transition section (UA) which differs from the first (inner) contour (K1), where the third (inner) contour (K3) transitions into the second (inner) contour (K2) in the transition section (UA), wherein the measuring tube body (10) has an (inner) transition section circumference (UAU) in the transition section (UA), wherein a circumferential length u1 of the (inner) measuring section circumference (MAU) and a circumferential length u2 of the (inner) transition section circumference (UAU) present at least in an end section (EAb) of the transition section (UA) adjacent to the measuring section (MA) are equal. Furthermore, the invention relates to a method for manufacturing a tubular component, in particular a measuring tube (1) for use in an ultrasonic measuring device (100), and an ultrasonic measuring device (100).

Description

[0001] The invention relates to a measuring tube, in particular for use in an ultrasonic measuring device, a method for manufacturing a tubular component, in particular a measuring tube, and an ultrasonic measuring device.

[0002] There are numerous ultrasound-based measuring devices. Lamb wave technology occupies a special position among them. It enables the generation and reception of ultrasound by transducer elements located outside the process, thus protecting these elements from aggressive media and eliminating the need for bores, pockets, or recesses in the measuring tube. Furthermore, the large-area vibration excitation of the tube wall, compared to conventional ultrasound technology, couples the acoustic energy into a correspondingly large area of ​​the adjacent medium, making the resulting sound beam relatively robust against particles (solids) and bubbles (gas inclusions) contained in the flow.

[0003] For certain measuring instruments, especially flow meters, it is advantageous to have off-center measuring paths. Such measuring paths allow, firstly, better coverage of the different areas of the measuring cross-section (outer, transition, inner regions), and secondly, reduce sensitivity to changes in the flow profile due to Reynolds number-dependent effects and upstream flow disturbances.

[0004] To implement such off-center measurement paths, especially those based on Lamb waves, cost-effectively, ideally with only two ultrasonic transducers, the measuring tube requires flat, parallel outer surfaces. Therefore, it is necessary to design at least parts of the measuring tube with flat sections.

[0005] Several ultrasonic flowmeters are already known in which measuring tubes with planar sections are used. For example, DE 198 23 165 A1 discloses an ultrasonic flowmeter with a measuring tube that has a square or rectangular inner cross-section in one measuring range. The end flanges of the ultrasonic flowmeter each have an opening with a quasi-conical shape that tapers towards the square or rectangular inner cross-section. DE 198 23 165 A1 aims to provide a measuring tube that can be fully emitted by clampable ultrasonic transducers. Furthermore, by selecting the appropriate tube wall geometry, a number of parallel ultrasonic beams can be generated to radiate the flow within the measuring tube in such a way that parallel summation is possible instead of Gaussian chord summation of individual paths.

[0006] DE 10 2017 115 431 A1 discloses a measuring device with a measuring tube which has a substantially rectangular internal cross-section in a measuring section and a non-rectangular internal cross-section in a connecting section. A transition section located between the measuring section and the connecting section has an internal cross-section identical to that of the measuring section at one end and an internal cross-section identical to that of the connecting section at the other. The internal cross-section of the transition section changes continuously along its entire length between the two ends. Thus, the transition between areas with different internal cross-sections is smooth and without hard, abrupt transitions or steps.This prevents increased flow separation and thus uneven flow profiles, high turbulence and pressure losses, which can distort measurements.

[0007] Furthermore, EP 3 388 794 A1 describes a measuring device for measuring the flow velocity of a fluid using a measuring tube. This tube has a rectangular measuring section, an inlet section with a first superelliptical transition shape, and an outlet section with a second superelliptical transition shape. The purpose of EP 3 388 794 A1 is to provide a measuring tube with a particularly homogeneous transition geometry from the circular section to the rectangular measuring section, thus preventing flow separation and achieving improved flow velocity measurement quality despite its short overall length.

[0008] Numerous manufacturing technologies exist for producing measuring tubes with planar outer surfaces, such as conventional internal machining (milling), wire EDM of an internal profile, extrusion of an internal profile, additive manufacturing, or investment casting combined with abrasive polishing. All these methods share the common characteristics of long production times and / or the need for a large amount of raw material to achieve the desired measuring cross-section. The transitions from the process connections, which are typically circular, to the section containing the ultrasonic measuring paths represent the most critical and complex part of the measuring tube, as a continuous and therefore fluid-mechanically efficient geometric transition must be created. Consequently, the production of such measuring tubes is expensive and often not competitive.

[0009] The invention is based on the objective of providing a remedy.

[0010] The problem is solved by the measuring tube according to claim 1, the method according to claim 15 and the ultrasonic measuring device according to claim 19.

[0011] The measuring tube according to the invention, in particular for use in an ultrasonic measuring device, comprises: - a measuring tube body for guiding a medium, wherein the measuring tube body has a connection section, wherein the measuring tube body has a non-angular, in particular round, first (inner) contour in a cross-section through the connection section, wherein the measuring tube body has a measuring section, wherein the measuring tube body has an (inner) measuring section circumference in the measuring section, wherein the measuring tube body in the measuring section has at least one planar outer surface, in particular for attaching at least one ultrasonic transducer, wherein the measuring tube body has a second (inner) contour in a cross-section intersecting the planar outer surface, wherein the measuring tube body has a transition section which is located between the measuring section and the connecting section, wherein the measuring tube body has a third (inner) contour in a cross-section of the transition section, which differs from the first (inner) contour, where the third (inner) contour transitions into the second (inner) contour in the transition section, wherein the measuring tube body has an (inner) transition section circumference in the transition section, where a circumference u1 of the (inner) measuring section circumference and a circumference u2 of the (inner) transition section circumference present at least in an end section of the transition section adjacent to the measuring section are equal in size.

[0012] Provided that the circumferential length u1 of the (inner) measuring section circumference and the (inner) circumferential length u2 of the end section of the transition section are identical, it can be ensured, particularly when using an internal high-pressure forming process, that the wall thickness of the measuring tube body remains unchanged in the measurement-relevant areas after forming. This means that during forming, the entire length of the measuring section is increased as much as possible and only slightly, without locally falling below the required minimum circumferential elongation. Thus, robust ultrasonic signals can be generated and evaluated, especially when the measuring tube is used in ultrasonic-based measuring devices.

[0013] Advantageous embodiments of the invention are the subject of the dependent claims.

[0014] One embodiment provides that the circumference u2 of the (inner) transition section circumference is constant at least over the entire end section of the transition section, in particular over the entire transition section.

[0015] One embodiment provides that the second (inner) contour is essentially rectangular.

[0016] One design provides that the third (inner) contour transitions into the second (inner) contour in the transition section from the first (inner) contour.

[0017] One embodiment provides that an (inner) cross-sectional area of ​​the measuring tube body in the transition section changes continuously in one direction of the longitudinal axis of the measuring tube body.

[0018] One embodiment provides that the measuring tube body has an (inner) outer surface, wherein an imaginary line extending in the direction of the longitudinal axis of the measuring tube body transitions continuously and without kinks on the (inner) lateral surface from the end section of the transition section into the adjacent initial section of the measuring section.

[0019] One design provides that the planar outer surface has at least one functional section, wherein, when using the measuring tube in an ultrasonic measuring device, the functional section is located between two ultrasonic transducers offset in the direction of the longitudinal axis of the measuring tube, wherein a measuring tube thickness in at least one functional section has a measuring tube thickness deviation of less than ±3% from a measuring tube thickness target value.

[0020] One embodiment provides that the measuring tube body has, in an (arbitrary) cross-section, a first (inner) diameter D1 and a second (inner) diameter D2 perpendicular to the first diameter D1, where in the measuring section the first diameter D1 is larger than the second diameter D2.

[0021] One embodiment provides that the first diameter D1 and the second diameter D2 in the connecting section are identical, where the first diameter D1 in the connecting section is identical to the first diameter D1 in the measuring section, where the second diameter D2 is a variable quantity, at least in the transition section.

[0022] One embodiment provides that the first diameter D1 assumes a constant value along the entire measuring tube body.

[0023] One embodiment provides that the second diameter D2 in each cross-section through the transition section fulfills a calculation rule according to which: D2(x)=(π2−1)⋅D1−(π−4)⋅R(x), where x ≤ 0 ≤ x ≤ L, where L describes the length of the transition section, where R(x) represents a variable radius of curvature to a curve point P describes where the curve point P lies on the third (inner) contour.

[0024] One embodiment provides that the planar outer surface in the transition section has a width B(x) that varies in the direction of the longitudinal axis of the measuring tube body, which fulfills a calculation rule according to which: B(x)=D1−2⋅R(x), where x ≤ 0 ≤ x ≤ L, where R(x) represents a variable radius of curvature to a curve point P describes where the curve point P lies on the third (inner) contour.

[0025] One embodiment provides that the radius of curvature R(x) along the transition section fulfills a calculation rule according to which: R(x)=R1+(D12−R1)⋅(1+cos(π⋅xL)) / 2, where R1 corresponds to a radius of curvature of the curve point P of the second (inner) contour in the measuring section.

[0026] One embodiment provides that the transition section has at least a first sub-section with a first measuring tube thickness t1, wherein the measuring section has at least a second sub-section with a second measuring tube thickness t2, wherein the first measuring tube thickness t1 is, in particular by at least 20%, greater than the second measuring tube thickness t2.

[0027] The inventive method for manufacturing a tubular component, in particular a measuring tube, preferably the measuring tube according to the invention, preferably for use in an ultrasonic measuring device, comprising: - Providing an outlet pipe with a pipe wall that assumes an (inner) outlet contour in a cross-section of a first section, where the (inner) starting contour is not angular, but in particular round, wherein the (inner) initial contour has a first circumferential length u1; - Deformation of the starting pipe, at least in the first section, by means of internal high-pressure forming to form the tubular component, in particular the measuring pipe, such that the pipe wall in the first section assumes a (inner) target contour, wherein the pipe wall (in the first section after deformation has at least one planar surface, where the (inner) target contour has a second circumferential length u2, where u1 = u2.

[0028] Only internal high-pressure forming, also known as hydroforming, provides a solution to the problem mentioned at the beginning: the process, consisting of the steps "inserting the starting tube," "closing the upper and lower mold halves," "closing the axial fluid inlets," "filling the tube and applying the forming pressure," "maintaining the forming pressure," "releasing the pressure and draining the forming fluid," "opening the fluid inlets and mold halves," and finally "removing the formed tube," typically takes place in just a few seconds. This results in very low process costs per formed tube, and a large number of formed tubes can be produced within a short time. The only requirement for this process is a ductile material, which, in the case of metals, is typically found in relatively thin walls.The latter in particular leads to a further reduction in costs, as thin-walled and therefore cost-effective standard pipes can be used for this purpose.

[0029] However, this is not normally guaranteed in internal high-pressure forming, because the essence of this forming process is to achieve the desired geometry through plastic deformation of the starting component, typically a piece of pipe, using very high internal pressure. Put simply, the starting component is "blown" into the desired shape against an external die (a two-part tool). This leads to locally varying wall thicknesses in areas of geometric change in the circular starting pipe, because the material is stretched and thus thinned by the geometric change.

[0030] At the same time, care must be taken to ensure that the circumference of the pipe slightly exceeds the yield strength over its entire length in order to guarantee tightly toleranced and reproducible forming results.

[0031] One design includes: - Machining the initial pipe, in particular by means of a turning process, at least in the first section, such that the pipe wall in the first section assumes a target wall thickness, wherein the initial pipe has at least a second section which remains unmachined, wherein the target wall thickness is less than a wall thickness of the pipe wall in the second section.

[0032] Another design includes: - Polishing of the output pipe, in particular an inner surface of the output pipe, wherein the polishing of the output pipe takes place before deformation.

[0033] Further cost savings can be achieved if the measuring instrument, due to its use in hygiene-sensitive applications, particularly in the food industry, requires inner surfaces with very high surface quality and / or low roughness. In such cases, pre-polished tubes can be used, whose surface quality is only slightly affected by hydrostatic cold forming. This eliminates the need for a final, costly polishing process of the entire measuring tube, including its process connections.

[0034] The ultrasound measuring device according to the invention for determining a property of a medium comprises: - a measuring tube according to the invention and / or produced using the method according to the invention; - a measuring unit with at least one transducer element for generating and / or receiving ultrasonic waves, wherein the measuring unit is arranged in the measuring section of the measuring tube; and - measuring electronics designed to determine the properties of the medium.

[0035] One embodiment provides that the measuring unit comprises a first and second transducer element, which are positioned in the measuring section in such a way that a measuring path connecting the first and second transducer elements and running through the interior of the measuring tube body is eccentric to a longitudinal axis of the measuring tube.

[0036] Off-center in the sense of the invention means that a principal axis of the ultrasound wave propagating through the interior of the measuring tube does not intersect the longitudinal axis of the measuring tube body itself.

[0037] One embodiment provides that the measuring unit comprises a first and second transducer element, which are positioned in the measuring section in such a way that a measuring path connecting the first and second transducer elements and running through the interior of a measuring tube body intersects a longitudinal axis of the measuring tube.

[0038] One embodiment provides that the ultrasonic measuring device uses acoustic surface waves, in particular Lamb waves, to determine the property.

[0039] One embodiment provides that the planar outer surface in the measuring section has a substantially constant width BMess, where the following applies to the width BMess: BMess≥2⋅λ⋅L1+λ is, for a wavelength λ of the acoustic surface waves used, in particular Lamb waves, and for a shortest path length L1 of the acoustic surface waves, in particular Lamb wave, between the first and second transducer element.

[0040] One embodiment provides that the first and / or second transducer element, in particular each, has a distance L2 to an end face of the measuring tube body, for which distance L2 is such that L2 ≥ N / 2 · λ for a wavelength λ of the acoustic surface waves used, in particular Lamb waves, and for a natural number N ≥ 6.

[0041] The invention is explained in more detail with reference to the following figures. They show: Fig. 1: a perspective view of an embodiment of the measuring tube according to the invention; Fig. 2: four cross-sections through an embodiment of the measuring tube according to the invention; Fig. 3: a perspective view of a section of a measuring tube according to the invention; Fig. 4: several sections from an embodiment of the measuring tube according to the invention; Fig. 5: a perspective view of an embodiment of the ultrasound measuring device according to the invention; Fig. 6: a perspective view of a further embodiment of the ultrasound measuring device according to the invention; Fig. 7: a flowchart of a method according to the invention for producing a tubular component; Fig. 8: three process steps of the inventive method for manufacturing a tubular component; and Fig. 9: three cross-sections through a tube which undergoes the process steps of an embodiment of the method according to the invention.

[0042] Fig. Figure 1 shows a perspective view of an embodiment of the measuring tube 1 according to the invention, which is intended for use in an ultrasonic measuring device (100, see Figure 1). Fig. 5) is suitable and equipped. Fig. Figure 2 shows four schematic cross-sections through the design of the measuring tube according to the invention. Fig. 1. The four cross-sections show the contour change along the longitudinal axis X of the measuring tube 1, starting from the first (inner) contour K1 of the connecting section AA (left outer) via two intermediate contours - where one intermediate contour assumes a third (inner) contour K3 - to the second (inner) contour K2 of the measuring section MA (right outer). Fig. Figure 3 shows a perspective view of a section of the measuring tube according to the invention. Fig. 1. Fig. Figure 4 shows several sections from an embodiment of the measuring tube according to the invention. Fig. 1. The square fields each represent a section of the cross-section through the measuring tube, depicting a part (or half) of the (inner) contour of the measuring tube body 10.

[0043] The measuring tube 1 comprises a measuring tube body 10 for guiding a medium. The measuring tube body 10 includes a tube wall 3, which defines a medium channel 13 through which the medium is guided when the measuring tube 1 is in use. An inner surface of the measuring tube body 10 is therefore in contact with the medium. Sensor components (e.g., ultrasonic transducers) can be arranged on an outer surface of the measuring tube body 10, which must not come into contact with the medium. The measuring tube body 10 is preferably made of metal. The measuring tube body 10 has a connection section AA, which, when the measuring tube 1 is in use in a pipeline, is in direct contact with the pipeline or, alternatively, with an intermediate adapter tube. The measuring tube 1 can have a connection element (not shown) in connection section AA, e.g., in the form of a connecting nozzle or a flange.According to the invention, the measuring tube body 10 has a non-angular, in particular round, first (inner) contour K1 in a cross-section through the connection section AA.

[0044] Furthermore, the measuring tube body 10 has a measuring section MA in addition to the connection section AA. In the illustrated configuration, the measuring section MA is located centrally between two end connection sections AA. The measuring section MA is characterized by the fact that, when the measuring tube 1 is used in a measuring device, the sensor components for determining a flow velocity-dependent or medium-specific measured quantity are arranged within it. Thus, the measuring section MA has different measurement-specific requirements than the connection section AA. If the measuring device is, for example, an ultrasonic measuring device, the transducer elements necessary for determining the property of the medium are arranged accordingly in the measuring section MA (see also Fig. 5) Accordingly, the wall thickness of the pipe wall 3 in the measuring section MA must also assume a constant target value in order to ensure the most robust possible ultrasonic signal. The measuring pipe body 10 has an (inner) measuring section circumference MAU with a circumferential length u1 in the measuring section MA. According to the invention, the measuring pipe body 10 is designed such that at least one planar outer surface AF is provided in the measuring section MA, in particular for attaching at least one ultrasonic transducer (20, see Fig. 5). In the measuring section MA, the measuring tube body 10 has a cross-section intersecting the planar outer surface AF, in which the measuring tube body assumes a second (inner) contour K2.

[0045] Furthermore, measuring tube 1 of the Fig. 1. A further planar outer surface oriented parallel to the planar outer surface AF and located on the other side of the measuring tube body 10. In addition, two further planar outer surfaces AFsenk are provided, which are themselves parallel to each other and simultaneously orthogonal to the two planar outer surfaces AF. The outer surfaces AF and AFsenk are suitable and configured to accommodate ultrasonic transducers.

[0046] Ultrasonic transducers typically have transducer elements in which at least the contact surfaces are planar. These can be acoustically coupled to the measuring tube body 10 extremely efficiently via the planar outer surfaces AF and AFsenk.

[0047] According to the invention, the measuring tube body 10 has a transition section UA ​​located between the measuring section MA and the connecting section AA. Especially with acoustic measuring principles, the transition section UA ​​also influences the measurement. In the transition section UA, the measuring tube body 10 assumes a third (inner) contour K3 in at least one cross-section. This differs from the first (inner) contour K1 at least in its shape. The third (inner) contour K3 transitions continuously into the second (inner) contour K2 in the transition section UA. For this purpose, the measuring tube body 10 has an (inner) transition section circumference UAU with a circumferential length u2 in the transition section UA. According to the invention, the circumferential lengths u1 and u2 are equal in at least one end section EAb of the transition section UA ​​adjacent to the measuring section MA.Two circumferential lengths are considered equal within the meaning of the invention if they deviate from a common target circumference by no more than 3%, and in particular by no more than 1.5%. It has been found that this condition ensures robust and reliable generation and evaluation of ultrasound signals.

[0048] The circumferential length u2 of the (inner) transition section circumference UAU can be constant at least over the entire end section EA of the transition section UA, and in particular over the entire transition section UA. Therefore, the circumferential length u2 of any (inner) transition section circumference UAU of the entire end section EA does not differ by more than 3%, and in particular not by more than 1.5%, from the circumferential length u1 in the measuring section MA.

[0049] As in the Fig. 1 and Fig. As shown in Figure 2, the second (inner) contour K2 can be essentially rectangular. Accordingly, the second (inner) contour K2 has four separate, straight or planar sub-contours in cross-section, with two sub-contours always running parallel to each other. An essentially rectangular contour within the meaning of the invention does not preclude rounded corners.

[0050] Furthermore, the third (inner) contour K3 can transition continuously from the first (inner) contour K1 to the second (inner) contour K2 in the transition section UA. This prevents steps that could cause disturbances in the flow profile and thus distort the measurement result.

[0051] Furthermore, for the reasons mentioned above, it may be required that an (internal) cross-sectional area QF of the measuring tube body 10 or of the medium channel 13 in the transition section UA ​​changes continuously in the direction of the longitudinal axis X of the measuring tube body 10.

[0052] The measuring tube body 10 has a lateral surface MF. This can be an inner lateral surface, i.e., in contact with the medium in the measuring insert, or an outer lateral surface, facing away from the medium. It may be required that an imaginary line L extending in the direction of the longitudinal axis X of the measuring tube body 10 on the lateral surface MF transitions continuously and without kinks from the end section EAb of the transition section UA ​​to the adjacent beginning section AAb of the measuring section MA. In the Fig. Figure 1 shows the imaginary line L on the outer surface. Alternatively, the imaginary line L can also extend along the inner surface. DE 10 2017 115 431 A1 requires that the inner cross-section of the transition section changes continuously over its entire length. According to the embodiment of the invention, it is further required that the imaginary line L not only runs continuously but is also kink-free, i.e., continuously differentiable.

[0053] The depicted planar outer surface AF has at least one functional section (FA, see Fig. 5) which, when the measuring tube 1 is used in an ultrasonic measuring device 100, is located between two ultrasonic transducers 20 offset in the direction of the longitudinal axis X of the measuring tube 1. It can be advantageous if the measuring tube thickness in the at least one functional section FA has a measuring tube thickness deviation of less than ±3% from a target measuring tube thickness value. For example, if the tolerance is undershot due to tolerance addition (minimum tube diameter + minimum tube thickness), significant "thinning" can occur in the forming process, which affects the ultrasonic signal.

[0054] The measuring tube body 10 has in an (arbitrary) cross-section a first (inner) diameter D1 and a second (inner) diameter D2 perpendicular to the first diameter D1 (see Fig. 4) It can be advantageous if the first diameter D1 in measuring section MA is larger than the second diameter D2. In this case, the first diameter D1 and the second diameter D2 are identical in the connecting section AA. This can be achieved, for example, by using a conventional round tube that remains essentially unchanged in terms of its forming process in the connecting section AA. The first diameter D1 in the connecting section AA remains identical to the first diameter D1 in measuring section MA, while the second diameter D2 is a variable dimension, at least in the transition section UA. Consequently, the second diameter D2 changes continuously within the transition section UA ​​until it has the same length as the second diameter D2 in the measuring section.

[0055] Furthermore, for the second diameter D2 in each cross-section through the transition section UA, it may be required that it fulfills a calculation rule according to which: D2(x)=(π2−1)⋅D1−(π−4)⋅R(x), where x ≤ 0 ≤ x ≤ L, where L describes the length of the transition section (UA), where R(x) describes a variable radius of curvature at a curve point P, and where the curve point P lies on the third (inner) contour K3. The radius of curvature is the radius of the circle of curvature passing through the curve point P. The circle of curvature is the circle that best approximates the curve at the curve point P. The center of this circle is called the center of curvature, and the point of tangency of the circle of curvature with the (inner) contour K3 includes, or is, the curve point P. If the calculation method is followed, the requirements for the circumferences can be met even in the transition sections UA (i.e., especially at cross-sectional changes), particularly when using an internal high-pressure forming process.

[0056] Furthermore, the planar outer surface AF in the transition section UA ​​can have a width B(x) that varies in the direction of the longitudinal axis of the measuring tube body 10, which fulfills a calculation rule according to which: B(x)=D1−2⋅R(x), where x 0 ≤ x ≤ L, where R(x) describes a variable radius of curvature to a curve point P, and where the curve point P lies on the third (inner) contour. The width B(x) lies in a cross-sectional plane of the measuring tube body 10.

[0057] Furthermore, the radius of curvature R(x) along the transition section can satisfy a calculation rule according to which: R(x)=R1+(D12−R1)⋅(1+cos(π⋅xL)) / 2, where R1 corresponds to a radius of curvature of the curve point P of the second (inner) contour (K2) in the measuring section (MA).

[0058] According to an advantageous embodiment of the Fig. 1 (see Fig. 7) The transition section UA ​​can have at least a first subsection TB1 with a first measuring tube thickness t1, and the measuring section MA can have at least a second subsection TB2 with a second measuring tube thickness t2. The two measuring tube thicknesses t1 and t2 differ. The first measuring tube thickness t1 can be, in particular, at least 20% greater than the second measuring tube thickness t2.

[0059] Due to its symmetrical geometry, the measuring tube body 10 can be divided by the section of the Fig. 3. Reconstruct. Thus, a plane SpieEb1 located at the end of the subsection and a plane SpieEb2 located perpendicular to the plane SpieEb1 and below the depicted subsection are each set up as a mirror plane.

[0060] The Fig. Figure 4 shows how the two diameters of the measuring channel 13 change along the longitudinal axis X. Diameter D1 has a variable length d2(x) and is perpendicular to diameter D2. Diameter D2 also has a variable length d1(x). In the initial section AA, the two lengths d1(0) and d2(0) are equal. In the measuring section, diameter D1 assumes a length d1(L) and diameter D2 a length d2(L). The length d1(x) can be constant across all sections, i.e., d(x) = d(0) = d(L). The length d2(x) can decrease as shown towards the measuring section until it reaches the value of length d2(L).

[0061] Fig. Figure 5 shows a perspective view of an embodiment of the ultrasonic measuring device 100 according to the invention for determining a property of a medium. The property of the medium can be a flow velocity-dependent measured quantity, such as a flow rate or a volumetric flow rate. Furthermore, or alternatively, the property of the medium can also be a physical property such as the speed of sound, the density and / or viscosity of the medium, the concentration of a component in the medium, particle density, a dissolution process, or degassing.

[0062] The ultrasonic measuring device 100 comprises a measuring tube 1 according to the invention and / or a measuring tube which is measured by means of a method according to the invention (see Fig. 7, Fig. 8 to Fig. 9) is manufactured. An illustration of the housing for protecting the electronic and sensor components, which encloses the measuring tube 1 in measuring section MA, has been omitted.

[0063] Furthermore, the ultrasonic measuring device 100 comprises a measuring unit 20* with at least one ultrasonic transducer 20 for generating and / or receiving ultrasonic waves. The measuring unit 20* is arranged in the measuring section MA of the measuring tube 1. The at least one ultrasonic transducer 20 is configured to couple ultrasonic waves into the measuring tube body 10 and / or to receive ultrasonic waves that propagate at least partially within the measuring tube body 10 and / or in the medium.

[0064] Furthermore, the ultrasonic measuring device 100 comprises measuring electronics 30, which are configured to determine the properties of the medium. The measuring electronics 30 can also be configured to provide an operating signal to the measuring unit 20*. For this purpose, the measuring electronics 30 can include an integrated circuit with electronic semiconductor components such as transistors, diodes, and / or other active and passive components, a microcontroller, and / or a microprocessor. The measuring electronics 30 are also electrically connected to the measuring system 20*, in particular to the at least one ultrasonic transducer 20.

[0065] Furthermore, the measuring unit 20* according to the invention comprises at least a first and second transducer element 21, 22. These can, for example, each have a piezoelectric element which is connected to the measuring electronics 30 and is configured to generate and / or detect ultrasonic waves.

[0066] As shown, the first and second transducer elements 21, 22 can be positioned in the measuring section MA such that a measuring path connecting the first and second transducer elements 21, 22 and running through the interior of a measuring tube body 11 or the medium channel intersects the longitudinal axis X of the measuring tube 1 or the measuring tube body 10 at least twice.

[0067] The Ultrasonic Measuring Device 100 can utilize acoustic surface waves, particularly Lamb waves, to determine the properties of a medium. A conventional pipe can naturally contain a multitude of vibration modes, in which the pipe wall exhibits, or can exhibit, Lamb waves—that is, mixed pressure and shear waves—such that the pipe wall is deflected both radially and longitudinally (Lamb wave vibration modes). These Lamb waves can be either symmetrical (S0, S1, S2, ...Sn) or asymmetrical (A0, A1, A2, ...An). Usually, several of the aforementioned Lamb wave vibration modes can each exhibit resonant frequencies that lie within the bandwidth of the respective ultrasonic transducer, i.e., close to its center frequency, or within the bandwidth of the excited ultrasonic waves.

[0068] Furthermore, it can be advantageous if the planar outer surface AF has a substantially constant width BMess at least in the measuring section MA, for which the following holds: BMess≥2⋅λ⋅L1+λ where λ is a wavelength of the acoustic surface waves used, in particular Lamb waves. The inequality applies for a shortest path length L1 of the acoustic surface waves, in particular Lamb waves, between the first and second transducer elements 21, 22.

[0069] Furthermore, it can be advantageous if the first and / or second transducer element 21, 22, in particular each, have a distance L2 to an end face SF of the measuring tube body 10, for which distance L2 is such that L2 ≥ N / 2 · λ, with a wavelength λ of the acoustic surface waves used, in particular Lamb waves, and a natural number N ≥ 6.

[0070] Fig. Figure 6 shows a perspective view of a further embodiment of the ultrasonic measuring device according to the invention. The embodiment shown is a slight modification of the one described in Fig. The illustrated ultrasonic measuring device comprises a measuring unit 20*, which has a first and second transducer element 21, 22, which together form a transducer pair, and a third and fourth transducer element 23, 24, which together also form a transducer pair. The transducer elements 21, 22, 23, 24 can each have a piezoelectric element, which is connected to the measuring electronics (not shown) and is configured to generate and / or detect ultrasonic waves.

[0071] The first and second transducer elements 21, 22 can be positioned in the measuring section MA such that a measuring path connecting the first and second transducer elements 21, 22 and running through the interior of a measuring tube body 11 or the medium channel runs off-center to a longitudinal axis X of the measuring tube 1.

[0072] The third and fourth transducer elements 23, 24 can also be positioned in the measuring section MA as shown, such that a measuring path connecting the third and fourth transducer elements 23, 24 and running through a measuring tube body interior 11 or medium channel runs off-center to the longitudinal axis X of the measuring tube 1.

[0073] Fig. Figure 7 shows a flowchart of a method according to the invention for manufacturing a tubular component, in particular a measuring tube, preferably a measuring tube according to the invention ( Fig. 1, Fig. 2, Fig. 3 to Fig. 4), preferably for use in an ultrasonic measuring device ( Fig. 5 and Fig. 6) The individual process steps are reflected in Fig. 7 and Fig. 8, therefore, reference is made to the reference symbols of these two figures below.

[0074] One embodiment of the method according to the invention comprises the following process steps: I. Providing an outlet pipe 2 with a pipe wall 3 which assumes an outlet contour AK in a cross-section of a first section A1. The outlet contour AK can be an inner or outer outlet contour of the pipe wall 3. According to the invention, the (inner) outlet contour AK is not angular, in particular not quadrilateral, but – as e.g. in Fig. 7 and Fig. Figure 8 shows a round shape. The (inner) starting contour AK has a first circumferential length u1. The starting tube 2 can be a conventional metallic tube.

[0075] Procedure steps II and III are optional. The order of these two steps can be reversed. II. Polishing of the outlet pipe 3, in particular the inner surface of the outlet pipe 3. Polishing can be carried out, for example, chemically using an acid bath or plasma polishing. A polished, medium-contacting surface is particularly important in hygienic applications. Alternatively, the outlet pipe 3 can also be polished mechanically using a polishing compound and a polishing device. Subsequent polishing of the already formed pipe is extremely complex. It has proven advantageous to perform the polishing step before internal high-pressure forming, as the roughness achieved by polishing is retained during internal high-pressure forming. III. Machining of the initial pipe 2, in particular by turning, at least in the first section A1, such that the pipe wall 3 in the first section A1 assumes a target wall thickness. The initial pipe 2 further comprises a second section A2 in which the pipe wall 3 assumes a wall thickness that is greater than the wall thickness (corresponding to the target wall thickness) in the first section A1. The initial pipe 2 can even remain unmachined in the second section A2. This additional machining step has the advantage that the desired pipe thickness tolerances in the measuring section for the final tubular component, in particular the final measuring tube, are already generated in the initial pipe. Thus, the target wall thickness targeted when machining the initial pipe 2 corresponds to the target wall thickness of the measuring section of the final measuring tube 1. IV. Deformation of the initial pipe 2, at least in the first section A1, by means of internal high-pressure forming to form the desired tubular component, in particular the measuring tube 1, such that the pipe wall 3 in the first section A1 assumes a (inner) target contour SK. The deformation of the initial pipe 2 is carried out such that the pipe wall 3 in the first section A1 has at least one planar surface F after deformation and that a second circumferential length u2 of the (inner) target contour SK resulting from the deformation is identical to the first circumferential length u1. The tubular component may also have further planar surfaces F that are oriented parallel or orthogonal to the planar surface shown.

[0076] The preceding deformation step can also include deformation of the initial tube 2 in the first section A1 when the forming tool required for internal high-pressure forming is closed. The forming tool is designed to hold the initial tube 2 in a predetermined position and defines the (inner) target contour SK during internal high-pressure forming, particularly in section 1. When the initial tube 2 is inserted into the forming tool and the tool is closed, the initial tube 2 can undergo deformation. The tube wall 3 in the cross-section of the first section A1 can, for example, assume an (inner) intermediate contour ZK in the cross-section of the first section A1 that deviates from the (inner) initial contour AK – e.g., in the shape of a dog bone, or at least neither rectangular nor round. This (inner) intermediate contour ZK, however, differs from the (inner) target contour SK. The (inner) target contour SK is then achieved through internal high-pressure forming. REFERENCE MARK LIST 1 measuring tube 2 Outlet pipe 3 pipe wall 10 measuring tube bodies 11 Measuring tube body interior 13 Medium channel 20 ultrasound transducers 21 first converter element 22 second converter element 23 third converter element 24 fourth converter element 20* measuring unit 30 Measuring electronics 100 Ultrasonic measuring device AA connection section MA measuring section EA End Section UA transitional phase AA connection section EAb End section AAb Initial section FA Functional Section A1 first section A2 second section MAU (inner) measurement section scope UAU (inner) transition section scope AF outer surface QF (Interior) cross-sectional area MF (inner) lateral surface F area SF front surface TB1 first sub-area TB2 second sub-area K1 first (inner) contour K2 second (inner) contour K3 third (inner) contour AK (inner) starting contour SK (inner) target contour ZK (inner) intermediate contour X Longitudinal axis L line QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 198 23 165 A1

[0005] DE 10 2017 115 431 A1 [0006, 0052] EP 3 388 794 A1

[0007]

Claims

Measuring tube (1), in particular for use in an ultrasonic measuring device (100), comprising: - a measuring tube body (10) for guiding a medium, wherein the measuring tube body has a connection section (AA), wherein the measuring tube body (10) has a non-angular, in particular round, first (inner) contour (K1) in a cross-section through the connection section (AA), wherein the measuring tube body (10) has a measuring section (MA), wherein the measuring tube body (10) has an (inner) measuring section circumference (MAU) in the measuring section (MA), wherein the measuring tube body (10) has at least one planar outer surface (AF) in the measuring section (MA), in particular for attaching at least one ultrasonic transducer (20), wherein the measuring tube body (10) has a second (inner) contour (K2) in a cross-section intersecting the planar outer surface (AF), wherein the measuring tube body (10) has a transition section (UA) which extends between The measuring section (MA) and connection section (AA) are locatedwherein the measuring tube body (10) has a third (inner) contour (K3) in a cross-section of the transition section (UA), which differs from the first (inner) contour (K1), wherein the third (inner) contour (K3) transitions into the second (inner) contour (K2) in the transition section (UA), wherein the measuring tube body (10) has an (inner) transition section circumference (UAU) in the transition section (UA), wherein a circumferential length u1 of the (inner) measuring section circumference (MAU) and a circumferential length u2 of the (inner) transition section circumference (UAU) present at least in an end section (EAb) of the transition section (UA) adjacent to the measuring section (MA) are equal. Measuring tube (1) according to claim 1, wherein the circumferential length u2 of the (inner) transition section circumference (UAU) is constant at least over the entire end section (EA) of the transition section (UA), in particular over the entire transition section (UA). Measuring tube (1) according to claim 1 or 2, wherein the second (inner) contour (K2) is essentially rectangular. Measuring tube (1) according to one of the preceding claims, wherein the third (inner) contour (K3) transitions in the transition section (UA) from the first (inner) contour (K1) to the second (inner) contour (K2). Measuring tube (1) according to one of the preceding claims, wherein an (inner) cross-sectional area (QF) of the measuring tube body (10) changes continuously in the transition section (UA) in the direction of a longitudinal axis (X) of the measuring tube body (10). Measuring tube (1) according to one of the preceding claims, wherein the measuring tube body (10) has an (inner) lateral surface (MF), wherein an imaginary line (L) extending in the direction of the longitudinal axis (X) of the measuring tube body (10) on the (inner) lateral surface (MF) transitions continuously and without kinks from the end section (EAb) of the transition section (UA) to the adjacent initial section (Aab) of the measuring section (MA). Measuring tube (1) according to one of the preceding claims, wherein the planar outer surface (AF) has at least one functional section (FA), wherein when the measuring tube (1) is used in an ultrasonic measuring device (100) the functional section (FA) is located between two ultrasonic transducers (20) offset in the direction of the longitudinal axis (X) of the measuring tube (1), wherein a measuring tube thickness in at least one functional section (FA) has a measuring tube thickness deviation of less than ±3% from a measuring tube thickness setpoint. Measuring tube (1) according to one of the preceding claims, wherein the measuring tube body (10) has in an (arbitrary) cross-section a first (inner) diameter D1 and a second (inner) diameter D2 perpendicular to the first diameter D1, wherein in the measuring section (MA) the first diameter D1 is larger than the second diameter D2. Measuring tube (1) according to claim 8, wherein the first diameter D1 and the second diameter D2 in the connecting section (AA) are identical, wherein the first diameter D1 in the connecting section (AA) is identical to the first diameter D1 in the measuring section (MA), wherein the second diameter D2 is a variable size at least in the transition section (UA). Measuring tube (1) according to claim 9, wherein the first diameter D1 assumes a constant value along the entire measuring tube body. Measuring tube (1) according to claim 9 or 10, wherein the second diameter D2 in each cross-section through the transition section (UA) satisfies a calculation rule according to which: D 2 ( x ) = ( π 2 − 1 ) ⋅ D 1 − ( π − 4 ) ⋅ R ( x ) , where x ≤ 0 ≤ x ≤ L, where L describes the length of the transition section (UA), where R(x) describes a variable radius of curvature to a curve point P, where the curve point P lies on the third (inner) contour (K3). Measuring tube (1) according to one of claims 9 to 11, wherein the planar outer surface (AF) in the transition section (UA) has a width B(x) that varies in the direction of the longitudinal axis (X) of the measuring tube body (10) and which satisfies a calculation rule according to which: B ( x ) = D 1 − 2 ⋅ R ( x ) , where x ≤ 0 ≤ x ≤ L, where R(x) describes a variable radius of curvature to a curve point P, where the curve point P lies on the third (inner) contour (K3). Measuring tube (1) according to claim 11 or 12, wherein the radius of curvature R(x) along the transition section (UA) satisfies a calculation rule according to which: R ( x ) = R 1 + ( D 1 2 − R 1 ) ⋅ ( 1 + cos ( π ⋅ x L ) ) / 2, where R1 corresponds to a radius of curvature of the curve point P of the second (inner) contour (K2) in the measuring section (MA). Measuring tube (1) according to one of the preceding claims, wherein the transition section (UA) has at least a first sub-section (TB1) with a first measuring tube thickness t1, wherein the measuring section (MA) has at least a second sub-section (TB2) with a second measuring tube thickness t2, wherein the first measuring tube thickness t1 is, in particular, at least 20% greater than the second measuring tube thickness t2. Method for manufacturing a tubular component, in particular a measuring tube (1), preferably a measuring tube (1) according to one of claims 1 to 14, preferably for use in an ultrasonic measuring device (100), comprising: - providing an output tube (2) with a tube wall (3) which assumes an (inner) output contour (AK) in a cross-section of a first section (A1), wherein the (inner) output contour (AK) is not angular, but in particular round, and wherein the (inner) output contour (AK) has a first circumferential length u1;- Deformation of the starting pipe (2) at least in the first section (A1) by means of internal high-pressure forming to form the tubular component, in particular the measuring pipe (1), such that the pipe wall (3) in the first section (A1) assumes an (inner) target contour (SK), wherein the pipe wall (3) in the first section (A1) has at least one planar surface (F) after deformation, wherein the (inner) target contour (SK) has a second circumferential length u2, where u1 = u2.; Method according to claim 15, comprising: - machining the starting pipe (2), in particular by means of a turning process, at least in the first section (A1) such that the pipe wall (3) in the first section (A1) assumes a target wall thickness, wherein the target wall thickness is less than a wall thickness of the pipe wall (3) in a second section (A2). Method according to claim 15 or 16, wherein the outlet pipe (2) remains unprocessed in the second section (A2), Method according to one of claims 15 to 17, comprising the method step:- polishing the starting tube (3), wherein the polishing of the starting tube (3) takes place before deformation. Ultrasonic measuring device (100) for determining a property of a medium (flow rate and physical properties such as speed of sound, density and viscosity; concentration, particle density, dissolution process, degassing), comprising: - a measuring tube according to one of claims 1 to 14 and / or manufactured by a method according to one of claims 15 to 18; - a measuring unit (20*) with at least one ultrasonic transducer (20) for generating ultrasonic waves and / or for receiving ultrasonic waves, wherein the measuring unit (20*) is arranged in the measuring section (MA) of the measuring tube (1); and - measuring electronics (30) configured to determine the property of the medium. Ultrasonic measuring device according to claim 19, wherein the measuring unit (20*) comprises a first and second transducer element (21, 22) which are positioned in the measuring section (MA) such that a measuring path connecting the first transducer element (21) and the second transducer element (22) and passing through a measuring tube body interior (11) is eccentric to a longitudinal axis (X) of the measuring tube (1). Ultrasonic measuring device according to claim 19, wherein the measuring unit (20*) comprises a first and second transducer element (21, 22) which are positioned in the measuring section (MA) such that a measuring path connecting the first transducer element (21) and the second transducer element (22) and passing through a measuring tube body interior (11) intersects a longitudinal axis (X) of the measuring tube (1). Ultrasonic measuring device according to claim 19 or 20, wherein the ultrasonic measuring device (100) uses acoustic surface waves, in particular Lamb waves, to determine the property. Ultrasonic measuring device according to claim 22, wherein the planar outer surface (AF) in the measuring section (MA) has a substantially constant width Bmess, wherein the width Bmess is such that Bmess ≥ 2 ⋅ λ ⋅ L 1 + λ is for a wavelength λ of the acoustic surface waves used, in particular Lamb waves, and for a shortest path length L 1 of the acoustic surface waves, in particular Lamb wave, between the first and second transducer element (21, 22). Ultrasonic measuring device according to claim 22 or 23, wherein the first and / or second transducer element (21, 22), in particular each, have a distance L2 to an end face (SF) of the measuring tube body (10), for which distance L2 is such that L2 ≥ N / 2 · λ for a wavelength λ of the acoustic surface waves used, in particular Lamb waves, and for a natural number N ≥ 6.

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