Device for contactlessly measuring the microstructure of moving material webs

Abstract

The invention relates to a device for contactlessly measuring the microstructure of a moving material web, for example a metal strip, comprising a specified material web spatial area (10) for arranging a moving material web, an x-ray source (12) and a collimator (14) for generating a collimated x-ray beam within an x-ray beam spatial area (18), said x-ray beam spatial area (18) specifying a beam axis (20), an overlap spatial area (22) which is formed by the material web spatial area (10) and the x-ray beam spatial area (18), and an energy-dispersive x-ray detector (24) which is arranged on the material web spatial area (10) side facing away from the x-ray source (12) and which comprises a measuring angle spatial area (26), wherein the measuring angle spatial area (26) assumes an angle, e.g. 20, relative to the x-ray beam spatial area (18), said angle being specified by the spatial direction (28) from the overlap spatial area (22) to the x-ray detector (24). The invention solves the technical problem of further improving the device and allowing a measurement for a material strip with a larger thickness. This is achieved in that the collimator (14) has an annular opening (17), the x-ray beam spatial area (18) is substantially conical, the cone specifies a cone axis as the beam axis (20), and the x-ray detector (24) is arranged in the extension of the beam axis (20).

Description

[0001] Device for non-contact measurement of the microstructure of moving material webs

[0002] The invention relates to a device for the contactless measurement of the microstructure of moving material webs, for example metal strips.

[0003] The mechanical properties of polycrystalline sheet products, such as flat-rolled strips made of steel or non-ferrous metals, are influenced by their microstructure. This results primarily from heat treatment during hot rolling or annealing. Process control is achieved, for example, using models and material temperature control. Due to inaccurate temperature measurements, varying dynamic behavior of the material, or deviations in the upstream processes, this approach is often insufficient and leads to defective products.

[0004] Direct control of the microstructure eliminates the above-mentioned error sources and improves yield. This requires a measurement of the microstructure parameters, such as the austenite content. An example of this is described in DE 199 41 736 Al. Specifically during the hot rolling of metal strip, X-rays penetrating the hot metal strip are recorded and evaluated online. The evaluation records crystallographic transformations and / or microstructural transformations and / or chemical transformations that occur at certain metal temperatures. From the knowledge of the degree of transformation or the transformation progression, suitable process control and / or regulation variables for process optimization are derived. If a process model is used as a basis, this model can be adapted online. Such a measurement can, for example,Electromagnetic measurement can be performed by measuring the electromagnetic properties of the material using a sensor beneath the strip and correlating them with the microstructural parameters. However, the measurement requires a small distance from the strip, so the usable range for measuring the austenite content is limited.

[0005] X-ray diffraction is a method regularly used in the laboratory to determine microstructure. It typically uses a backscattering technique, with the X-ray source and detector positioned on the same side of the sample. This method provides good resolution. However, this method only measures the microstructure on the surface of the sample, and the geometric arrangement of the sample relative to the measuring device must be very stable. Therefore, the method is not suitable for production.

[0006] Therefore, a method for angle-dispersive X-ray diffraction using the transmission method was developed. In this method, the sheet is irradiated with X-rays of constant energy and the resulting diffraction patterns are recorded using an X-ray area scan camera. The system is described in EP 3 465 181 B1 and can be installed in a protective housing in an annealing furnace. The emission energy of the tungsten tube of approximately 60 keV is used for the measurement. This energy is sufficient for measuring steel sheets with a thickness of up to 4 mm. At greater thicknesses, absorption is too great and the intensity of the residual radiation at the detector is no longer sufficient for angle-dispersive measurement. For example, it must be possible to measure the material strip with a greater thickness for measuring the austenite content in the cooling section of a hot strip mill.

[0007] To ensure sufficient signal intensity at the detector during X-ray diffraction using transmission techniques, even with thicker materials, the energy of the X-rays must be increased. Angle-dispersive X-ray diffraction uses a constant energy that depends on the element used in the X-ray tube's anode. Tungsten, which has been used to date, is the element with the highest atomic number and the highest emission energy typically used in X-ray tubes. Therefore, increasing the energy of the radiation is not possible.

[0008] Such higher energies can be generated with a linear accelerator. High intensities can be achieved, and the radiation is very monochromatic. However, due to the cost, such systems are only suitable for experimental measurements.

[0009] Furthermore, in angle-dispersive X-ray diffraction, the distances to the strip must be small, because, on the one hand, the size of the X-ray area camera must grow linearly with the distance. This leads to installation problems and a poor signal-to-noise ratio (SNR) of the individual camera pixels. On the other hand, as the distance between the X-ray source and the sample increases, the measurement spot size and the width of the diffraction peaks also increase.

[0010] Therefore, the present invention is based on the technical problem of further improving the device for the contactless measurement of the microstructure of moving material webs and of enabling a measurement with greater thickness of the material web.

[0011] The problem is solved by the use of a device for contactless measurement of the microstructure of a moving material web having the features of claim 1.

[0012] The device according to the invention for the contactless measurement of the microstructure of a moving material web is suitable, for example, for measuring a moving metal strip. For this purpose, the device has a predetermined material web space for arranging a moving material web. In particular, the device can have a guide device for guiding a moving material web in the material web space. For this purpose, the guide device preferably has at least one transport roller. However, the device can also be designed without its own guide device, wherein the material web to be measured runs suspended through the device and is conveyed and positioned in further devices upstream and downstream of the described device in the conveying direction.

[0013] The material web space area is therefore the spatial area within the device in which the material web moves and is arranged when the device is used, by feeding the material web in from the outside and feeding it out again.

[0014] The material path space area is defined within specified deviations from a target space area, whereby production-related fluctuations occur and are tolerated. The material path space area is therefore specified with upper and lower limits.

[0015] The device according to the invention further comprises an X-ray source and a collimator for generating a collimated X-ray beam within an X-ray beam space, wherein the X-ray beam space defines a beam axis. The X-ray beam space is also not strictly defined by boundaries, but rather exhibits a divergence due to the dimensions of the X-ray source itself and the dimensions of the collimator aperture.

[0016] Furthermore, the beam axis can be aligned essentially at a right angle to the material web area. This alignment results in a symmetrical arrangement of the measuring system within the device with respect to the conveyed material web.

[0017] The device according to the invention further comprises a

[0018] The overlapping area formed by the material web space and the X-ray beam space serves as the measuring area in the material web, also referred to as the measuring spot, when the device is used.

[0019] The angle between the X-ray beam space area and the flat material web space area is predetermined and defines the solid angles in which an X-ray intensity occurs due to Bragg diffraction at the crystal structure.

[0020] The device further comprises an energy-dispersive X-ray detector with a measurement angle range located on the side of the material web space area facing away from the X-ray source. The energy-dispersive X-ray detector records energy spectra of the received X-ray radiation.

[0021] Further, according to the invention, the device has the property that the measurement angle space region occupies an angle, for example, of 2°, to the X-ray beam space region, determined by the spatial direction from the overlap space region to the X-ray detector. The angle 2° is the same for all energies and all lattice spacings. Therefore, the detector detects the appropriate energy for the different lattice spacings with a certain intensity and resolution. This is because for each lattice spacing, there is an energy that is diffracted at the specified angle. The angle only changes if either the material strip or the detector position, i.e., the measurement setup, changes.

[0022] Thus, during the measurement, the angle between the X-ray beam, the material web, and the X-ray detector is predetermined and can be set to 20. The value of 20 is not dependent on a specific X-ray energy or specific grating plane spacing. The angle for the system results from the collimation and the geometric arrangement of the X-ray source, the material web, and the detector and is then fixed for a setup. The angle can be set so that the detected diffracted energies lie in a desired range, for example, an energy range higher than the characteristic tungsten radiation and whose energies are large enough to penetrate the thick material of the metal strip. Furthermore, the X-ray energy cannot be selected to be greater than the energy that the semiconductor detector can detect with acceptable efficiency.As the energy increases, the probability of a reaction between the radiation and the semiconductor material decreases, so that only a smaller part of the incoming radiation can be evaluated.

[0023] According to the invention, unlike the angle-dispersive arrangement, a constant diffraction angle is used instead of a constant radiation energy. At least a portion of the spectrum of the X-ray tube's radiation is then used for the measurement. The diffracted radiation is detected by an energy-dispersive X-ray detector, and the recorded spectra are analyzed for intensity maxima. The intensity maxima are each assigned to a value of a lattice plane spacing. This yields, at least in part, the parameters of the microstructures in the overlap space region within the material web.

[0024] According to the following Bragg equation, the diffraction reflections of the lattice planes result in signal peaks in the spectrum of the energy-dispersive X-ray detector. with dhki lattice plane spacing

[0025] Ehki Energy

[0026] 0 Diffraction angle c Speed ​​of light h Planck constant hkl Miller indices for describing lattice planes in a material To measure the X-ray energy spectrum of the diffracted beam, i.e., the radiation intensity as a function of the radiation energy, an energy-dispersive detector (EDX sensor) is used, which can be a semiconductor detector. If an X-ray photon is absorbed in the sensitive region of such a detector, electron-hole pairs are created there, the number of which is proportional to the energy of the photon. The spectrum of the X-ray detector plots the signal intensity as a function of the energy of the X-ray quanta.

[0027] By determining the energy of an intensity peak, the corresponding lattice plane spacing of the irradiated material can be determined.

[0028] The X-ray source used exhibits a characteristic intensity peak in the energy spectrum, depending on the anode material. Since this intensity peak overlays the diffraction reflections, only the continuous energy spectrum above the energy of the characteristic intensity peak is preferably used for the measurement.

[0029] Since the polycrystalline material of the material or metal sheet under investigation exhibits various phases or crystal structures, and these crystal structures, in turn, exhibit different lattice planes, a multitude of diffraction reflections arise in the X-ray energy spectrum. In the case of body-centered cubic (bcc) lattices (ferrite) and face-centered cubic (fcc) lattices (austenite), some of these diffraction reflections overlap.

[0030] This overlap can make it difficult to evaluate the intensities of the characteristic energy peaks in the X-ray energy spectrum for the quantitative determination of the phase fractions.

[0031] The quantitative determination of the phase fractions can therefore also be carried out via a

[0032] Phase analysis can be performed, which utilizes the entire functionality of the X-ray energy spectrum. The measured X-ray energy spectrum is mathematically reconstructed using characteristic functions. The characteristic functions are determined by measuring the X-ray energy spectrum on known samples with different microstructure components or polycrystalline samples, or by simulation. The phase components are calculated from the respective components of the characteristic functions using correlation coefficients.

[0033] In principle, in a described device, the collimator can have a single opening, preferably a substantially round opening. This design will be used below to explain the property underlying the invention. Due to the single collimator opening, the X-ray beam area is substantially linear and defines the beam axis. The term "substantially linear" here means that there is a widening of the X-ray radiation from a linear propagation due to an unavoidable divergence caused by the size of the X-ray source and the size of the collimator opening. Furthermore, the X-ray detector is arranged at a predetermined angle to the beam axis, preferably at a right angle.

[0034] If the specified angle of the measurement angle space to the beam axis corresponds to the angle 20 for a lattice plane spacing present in the material of the material web at a certain X-ray energy according to the Bragg equation, a signal or peak occurs in the spectrum of the energy-dispersive X-ray detector. The angle 20 results from the geometry, i.e. the angle between the incident X-ray beam within the essentially linear X-ray beam space and the connection from the X-ray detector to the overlap area or the intersection point of the incident X-ray beam with the material web. To fulfill the Bragg condition, the X-ray beam must have the energy matching the lattice plane spacing. The diffracted beam then hits the X-ray detector, which is preferably almost point-shaped.According to the device according to the invention, the collimator has an annular opening, in particular a circular opening, wherein the X-ray beam space is essentially conical in shape, and the conical in shape defines a conical axis as the beam axis. Furthermore, the X-ray detector is arranged in the extension of the beam axis. The term "essentially conical in shape" means that an expansion of the X-ray radiation from a conical in shape is present due to an unavoidable divergence. The divergence arises from the spatial dimensions of the X-ray source itself and the annular opening of the collimator.

[0035] Thus, to increase the intensity of the X-rays detected in the X-ray detector, a conical X-ray beam space is used instead of a substantially linear X-ray beam space. The collimator creates a similarly annular measuring spot in the overlapping space in the material web. The X-rays diffracted toward the X-ray detector positioned on the beam axis all have the same diffraction angle 2° and therefore the same X-ray energy spectrum, especially in a precisely rotationally symmetrical setup.

[0036] Due to tolerances and changes in the geometric design of the measuring setup, such as thermal expansion, it may not be possible to maintain rotationally symmetric alignment with sufficient accuracy over time. Since the diffraction angles for all beams are no longer the same in this case, the X-ray energy spectra in the measured spectra are shifted relative to each other. The diffraction reflections in the resulting X-ray energy spectra measured by the detector are then broadened.

[0037] Therefore, in a further embodiment of the device, a preferably two-dimensional movement device is provided for moving the X-ray detector in a plane substantially perpendicular to the beam axis. The preferably almost point-shaped X-ray detector can thus be adjusted and tracked via the movement device, if necessary regularly and automatically. In this case, the X-ray detector is displaced in the longitudinal and transverse directions by means of an algorithm of a control unit until the width of the maxima or peaks of the diffraction reflections in the spectrum of the energy-dispersive X-ray detector is minimal. Adjustment using the movement device can be carried out both during breaks in the use of the device, for example during rolling breaks in the system in which the device is used, on a sample, and in small steps during ongoing measurements on the moving material web.

[0038] In a further embodiment of the described device, the X-ray detector has a one-dimensional or two-dimensional sensor matrix. Thus, the optimal position of the X-ray detector can also be determined using an imaging one- or two-dimensional energy-dispersive X-ray detector. The optimal position can be determined by parallel evaluation of the individual pixels of the sensor matrix. The pixel that generates the narrowest and highest energy peaks in the spectrum is in the optimal position. With a sufficiently large detector, adjusting the detector position using the movement device can be omitted.

[0039] In a further embodiment of the device, the X-ray detector has at least two sensors arranged at a distance along the beam axis. This means that several X-ray detectors, preferably almost point-shaped or designed as a sensor matrix, can be arranged one behind the other. This allows the utilized intensity of the X-ray radiation to be multiplied according to the number of detectors. The distance to the overlapping spatial area and the different solid angles must be taken into account. With this arrangement of at least two X-ray detectors, the signal noise can be further reduced and / or the measuring speed increased. Furthermore, due to production and transport reasons, the position of the material web within the material web spatial area can change during use of the device, particularly in the direction of the beam axis.This changes the angle 20°. For example, the angle 20° increases when the material band shifts toward the X-ray detector. This, in turn, leads to a shift in the position of the energy peaks in the spectrum of the energy-dispersive X-ray detector.

[0040] This problem can be addressed in the described device by making the distance between the X-ray source and the material web space smaller than the distance between the material web space and the X-ray detector. This achieves an asymmetrical arrangement of the material web in the device and reduces the influence of the change in the position of the material web on the detected diffraction angle and thus on the generated energy spectra. This is because X-rays are always scattered at all angles. However, the preferably point-shaped detector only covers a region of the diffracted radiation. This region shifts as the material web moves toward the detector.

[0041] In particular, to minimize the influence of the movement of the material web within the material web space, the X-ray detector can be arranged at a distance at least twice the distance from the X-ray source to the material web space. This arrangement has the additional advantage of also meeting typical installation conditions, where the installation space below the material web space, also known as the roller table, is limited and the greatest possible distance should be maintained above the hot material of a hot strip in the material web space.

[0042] A further advantage of energy-dispersive measurement is that the geometry of the device can be adapted almost arbitrarily to the geometric specifications of the roller conveyor. The design of the annular collimator allows the diffraction angle to be adjusted, thus enabling different arrangements of the X-ray source and X-ray detector.

[0043] The remaining shift in the energy peaks in the X-ray detector spectrum caused by the change in the position of the material web, as well as a shift due to the lattice expansion of the crystal structure, can be compensated for by applying correction factors during phase analysis. The correction factors can be determined from the diffraction pattern or by an external measurement, e.g., using a distance or temperature measuring device.

[0044] In the following, the invention is explained using exemplary embodiments with reference to the drawing. In the drawing,

[0045] Fig. 1 shows an embodiment of a device for contactless measurement of the microstructure of a moving material web with a substantially linear X-ray beam space area,

[0046] Fig. 2 shows an embodiment of a device for contactless measurement of the microstructure of a moving material web with an essentially conical X-ray beam area,

[0047] Fig. 3 shows an embodiment of a device for contactless measurement of the microstructure of a moving material web with a movement device for the X-ray detector,

[0048] Fig. 4 shows an embodiment of a device for contactless measurement of the microstructure of a moving material web with a one-dimensional sensor matrix of an X-ray detector, Fig. 5 shows an embodiment of a device for contactless measurement of the microstructure of a moving material web with two X-ray detectors arranged along the beam axis,

[0049] Fig. 6a and b an embodiment of a device for contactless measurement of the microstructure of a moving material web with two different vertical positions of the material web space area,

[0050] Fig. 7 shows an embodiment of a device for contactless measurement of the microstructure of a moving material web with an arrangement in a C-shaped measuring bracket and

[0051] Fig. 8 shows an embodiment of a device for contactless measurement of the microstructure of a moving material web as part of a heat treatment device.

[0052] In the following description of the various embodiments according to the invention, components and elements with the same function and the same mode of operation are provided with the same reference numerals, even if the components and elements in the various embodiments may have differences in their dimensions or shape.

[0053] Fig. 1 shows an embodiment of a device 2 for contactless measurement of the microstructure of a moving material web in the form of a metal strip 4 to explain the measuring principle.

[0054] A guide device with two pairs of rollers 6 and 8 serves to guide the moving metal web 4 in a predetermined material web space area 10. The material space area 10 is to be understood as the space area predetermined in the device 2 in which the metal strip 4 is to be transported.

[0055] Due to spatial fluctuations of the metal strip 4, the spatial area is not precisely defined, but rather exhibits a range of fluctuations. The material web spatial area 10 is shown in Fig. 1 with dashed lines.

[0056] The device 2 comprises an X-ray source 12 and a collimator 14 with a round collimator opening 16 for generating a collimated X-ray beam within an X-ray beam space 18, wherein the X-ray beam space 18 defines a beam axis 20. Dashed lines indicate that the X-ray beam space 18 has an angular extent defined by the two-dimensional X-ray source 12 and the likewise two-dimensional collimator opening 16 of the collimator 14.

[0057] The X-ray beam area 18 is thus essentially linear and defines the beam axis 20. "Essentially linear" means that a deviation from a linear propagation of the X-ray radiation is present due to an unavoidable divergence.

[0058] In the illustrated embodiment, the beam axis 20 is essentially at a right angle to the material web space area 10. However, the beam axis can also be set at a different angle, although the right angle is preferred only as an example.

[0059] The material web space area 10 and the X-ray space area 18 form an overlap space area 22, in which the interaction between the X-ray radiation and the microstructure of the metal takes place within the material of the metal strip 4 during operation of the device 2. The overlap space area 22 is therefore the measurement area in the metal web 4 during operation.

[0060] Furthermore, Fig. 1 shows an energy-dispersive X-ray detector 24 arranged on the side of the material web space area 10 facing away from the X-ray source 12. Various types of semiconductor detectors are used as the energy-dispersive X-ray detector 24. Cadmium telluride (CdTe) semiconductor detectors and cadmium zinc telluride (CZ) detectors are preferred at room temperature. High-purity germanium (HPGe) detectors can also be used, although these require cooling with liquid nitrogen.

[0061] Furthermore, the X-ray detector 24 is arranged at a predetermined angle 20 to the beam axis 20. The X-ray detector 24 defines a measurement angular spatial range 26 through its aperture, which is determined by the spatial direction or measurement direction 28 and the angular extent shown in dashed lines. The measurement angular spatial range 26 is determined from the boundaries of the overlap spatial range 22 to the opening of the X-ray detector 24. This is because the angular extent of the measurement angular spatial range 26 is predetermined by the extent of the overlap spatial range 22, by the angular dispersion of the X-ray beam spatial range 18, and by the aperture of the X-ray detector 24.

[0062] The measurement angle spatial region 26 therefore occupies an angle of 20° to the X-ray beam spatial region 18, determined by the spatial direction from the overlap spatial region 22 to the X-ray detector 24. The observed angle 20° does not depend on the parameters of the X-ray energy and the lattice spacing. The angle 20° is determined by the arrangement of the X-ray beam with the beam axis 20° relative to the X-ray detector 24. Depending on the lattice spacing of the microstructure in the metal strip 4, different energies or wavelengths of the X-ray radiation are diffracted from the continuous X-ray energy spectrum at precisely this angle.

[0063] The angle 2° is thus specified, whereby the expected diffraction is calculated at the diffraction angle 0, and the angle is specified as 2° for the expected diffraction on the material to be examined and the available X-ray energies. Fig. 2 shows an embodiment of a device 2 according to the invention. In contrast to Fig. 1, no guide device with roller pairs is initially provided; the metal web 4 is fed into and removed from the side of the device. The device 2 therefore operates with a "floating" metal web 4, which is guided and positioned in the direction of movement upstream and downstream of the device 2 by further production devices.

[0064] Furthermore, according to Fig. 2, the collimator 14 has a circular opening 17. The X-ray beam area 18 is therefore essentially conical in shape, and the conical in shape defines a conical axis as the beam axis 20. The term "essentially conical in shape" here means that a deviation from a conical propagation of the X-ray radiation occurs due to an unavoidable divergence. For reasons of clarity, the X-ray beam area 18 is not depicted with dashed boundary lines in Fig. 2 and all subsequent figures.

[0065] The overlapping space region 22, and thus the space region irradiated in the metal track 4, is ring-shaped. Furthermore, the X-ray detector 24 is arranged in the extension of the beam axis 20. This results in a—ideally—symmetrical structure. This is because, at a solid angle of 20, the diffracted X-rays, starting from the ring-shaped overlapping space region 22, are also directed in a conical shape onto the X-ray detector 24. This increases the measured intensity of the diffracted X-rays compared to the arrangement shown in Fig. 1.

[0066] The X-ray detector 24 defines, through its aperture, a conical-shaped measurement angular space region 26 (here without delimiting lines as shown in Fig. 1), which is determined by the measurement direction 28, which essentially coincides with the beam axis, and the angular extent of the collimator opening 17. The angular extent of the measurement angular space region 26 is also determined by the angular dispersion of the X-ray beam space region 18, by the extent of the annular overlap space region 22, and by the aperture of the X-ray detector 24.

[0067] Fig. 3 shows a further embodiment with an expanded configuration compared to Fig. 2 with a two-dimensional movement device 30 for moving the X-ray detector 24 in a plane substantially perpendicular to the beam axis 20. The movement device 30 is shown schematically with two intersecting arrows.

[0068] With the help of the movement device 30, the position of the X-ray detector 24 can be changed in order to obtain the best possible signal in the spectrum of the energy-dispersive X-ray detector 24.

[0069] Alternatively or in addition to the configuration in Fig. 3, Fig. 4 shows an embodiment in which the X-ray detector 24 has a two-dimensional sensor matrix 25. By means of the separate energy-dispersive sensors of the sensor matrix 25, several spectra are recorded and evaluated in parallel. Thus, with a stationary arrangement of the sensor matrix 25, the sensor that generates the best signal can be determined. The spectra subsequently measured and determined by this sensor are then selected for measuring the microstructure. The camera-like sensors of the sensor matrix 25 are shown schematically and can also be significantly smaller in relation to the device shown. In particular, the sensor matrix can also be formed from a sensor chip with a plurality of individual X-ray detectors on one chip.

[0070] Fig. 5 shows a further preferred embodiment of the device 2. In contrast to the previously described embodiments, the X-ray detector 24 has at least two sensors 27 arranged at a distance along the beam axis 20. Slightly different angles 20i and 202 apply to both sensors 26, which result in spectra that are shifted relative to each other. However, this shift is calculable and can be compensated for. Overall, this arrangement of the sensors 27 again results in improved measurement results.

[0071] Figures 6a and 6b show the effect that a vertical shift in the position of the metal strip 4 within the device 2 has on the measurement results. For each of the two vertical positions shown, a different angle of 20i and 202 applies. Since the vertical fluctuations of the metal strip 4 within the device 2 occur unpredictably, correction functions used in signal processing must be applied to compensate for the resulting deviations.

[0072] One measure to reduce this effect is to make the distance between the X-ray source 12 and the material web space area 10 smaller than the distance between the material web space area 10 and the X-ray detector 24. A distance at least twice as large is preferred. The greater the distance between the material web space area 10 and the X-ray detector 24, the less significant the effect of vertical fluctuations in the metal strip 4.

[0073] Fig. 7 shows an application of the device 2 for installation in a hot strip mill using a C-shaped measuring bracket 40.

[0074] The lower boom 42 of the C-shaped measuring bracket 40 contains the X-ray source 12 and the collimator 14 with the annular collimator opening 17. Above the X-ray source 12, an X-ray beam is formed in the conical X-ray beam space 18. The X-ray beam strikes the metal strip 4, forms an annular measuring point in the overlap area 22, and is diffracted at a diffraction angle of 20 to the X-ray detector 22. To minimize the influence of the vertical movement of the metal strip 4, the X-ray detector 24 is arranged in the upper boom 44 at a distance at least twice the distance from the X-ray source 12 to the metal strip 4. This also accommodates typical installation conditions where the installation space below the material web space area 10, also referred to as the roller table, is limited and the greatest possible distance from the X-ray detector 24 should be maintained above the hot metal strip 4.

[0075] Upstream of the X-ray detector 24, the beam is limited by another collimator 46, reducing the width of the diffraction reflections. The X-ray detector 24 is equipped with a movement device 30 for automatically adjusting the detector position. This also reduces the influence of interfering scattered radiation, which can also occur at other locations within the device.

[0076] The measuring bracket 40 can be moved into the rolling mill for measurement. In this position next to the rolling mill, the detector position can be checked and adjusted regularly. In addition to the detector position, the measurement accuracy and / or reproducibility of the measurements can also be checked using reference samples outside the rolling mill.

[0077] Fig. 8 shows an application of device 2 in a heat treatment device 50. Here, the X-ray source 12 and the X-ray detector 24 are arranged outside the heat treatment device 50. The beams pass through windows 52 and 54 with a low absorption coefficient. As described above, the conical geometry of the X-ray radiation allows for large separations, and the required size of the windows 52 and 54 is small. The alignment of the X-ray detector 24 to the X-ray source 12 is again achieved via the movement device 30.

Claims

P a t e n t a n s p r ü c h e 1. A device for the contactless measurement of the microstructure of a moving material web, for example a metal strip, with a predetermined material web spatial region (10) for arranging a moving material web, with an X-ray source (12) and a collimator (14) for generating a collimated X-ray beam within an X-ray beam spatial region (18), wherein the X-ray beam spatial region (18) predefines a beam axis (20), with an overlap spatial region (22) formed by the material web spatial region (10) and the X-ray beam spatial region (18), with an energy-dispersive X-ray detector (24) arranged on the side of the material web spatial region (10) facing away from the X-ray source (12) and having a measuring angle spatial region (26), wherein the measuring angle spatial region (26) assumes an angle, for example of 20, to the X-ray beam spatial region (18) predetermined by the spatial direction (28) from the overlap spatial region (22) to the X-ray detector (24).characterized in that the collimator (14) has an annular opening (17), wherein the X-ray beam space region (18) is substantially conical in shape and the conical shell defines a cone axis as the beam axis (20), and in that the X-ray detector (24) is arranged in the extension of the beam axis (20).

2. Device according to claim 1, characterized in that a, preferably two-dimensional, movement device (30) is provided for a movement of the X-ray detector (24) in a plane substantially perpendicular to the beam axis (20).

3. Device according to one of claims 1 or 2, characterized in that the X-ray detector (24) has a one-dimensional or two-dimensional sensor matrix (25).

4. Device according to one of claims 1 to 3, characterized in that the X-ray detector (24) has at least two sensors (27) arranged at a distance along the beam axis (20).

5. Device according to one of claims 1 to 4, characterized in that the distance between the X-ray source (12) and the material web space area (10) is smaller than the distance between the material web space area (10) and the X-ray detector (24).

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