INSPECTION DEVICE FOR INSPECTING FLAT-EXTENDING METALLIC OBJECTS

Description

[0001] The present invention relates to an inspection device for inspecting flat, metallic objects, in particular sheets or walls, wherein the inspection device is designed to be inaccessible to pipelines by omitting at least one propulsion element that at least substantially fills an inner pipeline cross-section, comprising at least one functional unit for recording object information and comprising at least one magnet unit with a plurality of magnets provided for magnetizing the object.

[0002] Such an inspection device for non-destructive testing is designed, for example, as a handheld inspection device with at least one handle or as a stationary device with a stationary frame. Alternatively or additionally, it can be an inspection device that is guided along the outside of a pipeline, a metal wall, or a metal sheet by means of a handle or other guide or drive device, or it can be an inspection device that actively moves independently along the outside of the pipeline by means of at least one drive element. For the purposes of this application, "pipeline-inaccessible" means that the inspection device does not constitute a pig that moves passively or actively through a pipeline.A passive movement of a pig through a pipeline is generated in particular by a propulsion element that at least substantially fills an inner, free pipeline cross-section and against which a fluid moving in the pipeline can press.

[0003] Inspection devices according to the preamble of claim 1 comprise a magnetic unit for magnetizing the metallic object to be tested. Depending on the type of non-destructive testing, the magnetic field generated in the object produces signals that can be recorded or processed by the functional unit. The magnetic fields required to magnetize the object can be generated by electromagnets and / or permanent magnets. A disadvantage is that these require comparatively high energy at high field strengths and are therefore large and heavy.

[0004] From the subsequently published WO 2021 / 116433, an inspection pig is known which has a functional unit for recording pipeline information and at least one magnet unit with a plurality of magnets provided for magnetizing the pipeline wall.

[0005] From DE 10 2013 011 626 A1 an inspection pig is also known which comprises an eddy current braking unit formed by magnets.

[0006] DE 10 2007 053 584 A1 discloses a device and a method for material testing and / or thickness measurement on a test object having at least electrically conductive and ferromagnetic material components.

[0007] US 6,523,650 B1 discloses an eddy current brake unit, wherein the adjacent magnets are angled at 90°.

[0008] It is an object of the present invention to provide an inspection device which does not have the aforementioned disadvantages.

[0009] The object is achieved by an object according to claim 1, advantageous embodiments of the invention can be found in the subclaims and the description.

[0010] This object is achieved by an inspection device according to the preamble of claim 1, in which the magnet unit has a plurality of segments, each with at least one magnet, and the magnetization directions of adjacent segments are angled or tilted relative to one another by at least approximately 90°, preferably by exactly 90°. By forming such a magnet unit, the magnetic flux densities can be increased, resulting in a range of possible arrangements in which the flux densities in the object are increased. The magnetic field acting on and generated within the object is stronger than with conventionally used magnets, so that the entire magnet unit can be shorter and smaller, and thus the inspection device can be constructed more lightly.

[0011] The magnet unit can also be part of the functional unit, or one or more parts of the functional unit can be arranged in the magnet unit or be part of it. Depending on the technology used, the functional unit further comprises, in particular, one or more units necessary for generating excitation signals and / or for recording object information in the form of measurement signals, e.g., one or more sensors (e.g., transmitting and / or receiving transducers), control and / or evaluation electronics, energy storage, transmission and / or interface means, etc.

[0012] Preferably, a segment of the magnet unit comprises a single magnet, but it can also comprise several magnets, in particular those with the same direction of magnetization.

[0013] Adjacent magnets are magnets that are separated by a magnet holder or are directly touching each other.

[0014] The magnets of the segments or the magnet unit are preferably permanent magnets, in particular neodymium magnets. In particular, the poles of two segments that are directed towards each other and are separated by a further segment have identical polarity, i.e. they both form either north or south poles that are directed towards each other, with a magnet from a further segment being arranged between the magnets or segments. In particular, this segment arranged in between also points towards the surface of the object with its own north pole or south pole side during operation. This already results in an initial focusing of the magnetic field lines towards the surface during operation, while on the side of the magnet unit facing away from the surface, the magnetic field lines are weakened.Such magnet units constructed in the manner of Halbach arrays already lead to higher flux densities and higher magnetic field strengths in the object, which means that the magnet units and thus the corresponding pig segments can be built shorter.

[0015] In the following, the segments whose magnets are provided with a magnetization direction (north-south direction) essentially perpendicular to the surface of the object to be inspected (during operation) are also referred to as vertical segments. The magnetization direction, which is indicated by an imaginary line from the north to the south pole, lies within an angular range of ± 15° around a perpendicular to the surface of the object. Accordingly, the magnetization direction is inclined by 75° to 105°, preferably by 90°, to the surface of the object to be inspected when the inspection device and object move relative to each other during operation. The magnetization direction of a segment corresponds to the magnetization direction of the magnet(s) forming the segment.

[0016] The vertical segment leads to the introduction of magnetic field lines that are directed approximately or directly perpendicular to the surface of the object during operation, which is advantageous, for example, for EMAT wall thickness measurements. In this case, approximately perpendicular means, as above, within a range of + / - 15° around a vertical line.

[0017] An inspection device according to the invention is further improved if, according to a further embodiment of the invention, the vertical segment is delimited by a focusing element toward the surface of the object to be inspected (during operation). Such a focusing element, in particular made at least substantially of steel, serves to further focus and amplify the magnetic field lines. The focusing element is, in particular, magnetizable.

[0018] Surprisingly, it has been shown that the additional use of the focusing element allows for very high flux densities to be achieved, much better than with magnet arrangements such as a Halbach array without focusing element(s), where the maximum application of the magnetic field is limited by the saturation flux density. The efficiency, i.e., the magnetic field strength measurable in the object during operation, increases by up to a factor of 3. Conversely, units used to achieve previous flux densities in the object's material can be significantly smaller than before, which in turn improves the portability and / or design of the inspection device.

[0019] Accordingly, a design of an inspection device according to the invention in which the focusing element is bounded by a magnet on at least three sides, with the poles of the magnets located on these sides having identical polarity, but in particular simultaneously belonging to different segments, results in a drastic increase in the magnetic field strengths and flux densities in the object to be inspected during operation. Such a device according to the invention is significantly shorter than prior art devices generating the same forces.

[0020] The flux densities present in the focusing element, which is constructed at least substantially from steel comprising cobalt and iron, are in particular up to 2.5 T, but at least up to 2.3 T. For example, a magnet unit equipped with nine magnets arranged one behind the other, in which successive magnets have magnetization directions tilted relative to one another and which are arranged in a type of Halbach array, results in an attractive force of up to 45 kN for the object. A magnet unit additionally equipped with focusing elements as described above, but otherwise constructed in the same sequence and magnetization direction of the equally strong magnets, results in attractive forces of 180 kN.

[0021] Inspection devices equipped with corresponding magnetic units can therefore be significantly shorter and lighter, making them easier to carry, for example, while still maintaining the same forces.

[0022] For the purpose of further focusing the magnetic field lines toward or away from the surface of the object to be inspected, according to a further embodiment of the invention, the magnet units can have a frame made of a magnetizable material in a longitudinal direction parallel to the surface of the object to be inspected, which frame delimits the magnets of the magnet unit. In a view transverse to the longitudinal direction, corresponding frames are present in the magnet unit, for example, at the front and rear in the direction of movement.

[0023] Alternatively or additionally, a preferably elongated magnet unit of an inspection device according to the invention can also be oriented transversely to the longitudinal direction, in which case its outer side is adapted, for example, to the curvature of an outer surface of a pipeline wall to be observed. Magnet units designed with their longitudinal extension parallel to the longitudinal direction can also be provided with an outer side whose curvature is adapted to the curvature of an outer surface of a pipeline wall or of a curved sheet metal.

[0024] The frame as well as the focusing element are made in particular of cobalt-iron steel, but at least and in particular of magnetizable steel.

[0025] According to a further development of the invention, the magnet unit is provided with a sensor for recording object information, i.e. sensor data or inspection data. The sensor of the functional unit is thus also assigned to the magnet unit. This sensor is arranged in particular in the focusing element, in a recess thereof and / or on the focusing element and is thus arranged centrally in or on the magnet unit. According to the above, it follows that the magnetization directions of the segments not designed as vertical segments preferably run parallel or approximately parallel to the longitudinal direction, which corresponds to the preferred direction of movement during operation. Such a design can be present, for example, when the functional unit is designed for an EMAT test and / or wall thickness sensor.

[0026] The magnet unit preferably has at least three magnets arranged one behind the other in its longitudinal direction. According to a further embodiment, in particular, seven magnets are arranged one behind the other, so that there are preferably two focusing elements bounded by the north poles of permanent magnets and one focusing element bounded by the south poles. Furthermore, it is particularly possible to have respective focusing elements laterally bounded not only by three but also, in particular, by five magnets.

[0027] While magnet units for inspection are typically cuboid, block-shaped and / or elongated, according to a further embodiment of the invention it may be advantageous to form ring-shaped magnet units in order to specifically generate corresponding magnetic fields in the surface of the object.

[0028] To prevent adhesion effects on the observed surface of the object, a pig according to the invention, according to a further exemplary embodiment, has at least one spacer, which is preferably adjustable with respect to the distance of the magnets from the wall or surface, and via which the magnet unit can be positioned at a distance from the surface of the object to be inspected. To cover a curved contour of the object, e.g., an outer surface of a pipeline, the inspection device can again have several magnet units arranged next to one another, viewed in the direction of movement occurring during operation.

[0029] Further advantages and details of the invention can be found in the following description of the figures. Schematically shown: Fig. 1 a spacer with a magnet unit of a device according to the invention in a perspective view, Fig. 2 the device according toFig. 1 in a partially cut-away view, Fig. 3 a perspective view of a further magnet unit with sensors, Fig. 4 a schematic diagram of the use of an inspection device according to the invention, Fig. 5 a simplified view of a magnet unit of a further device according to the invention in a partially cut-away view, Fig. 6 a magnet unit of a further inspection device according to the invention, Fig. 7 a view of a magnet unit of a further object according to the invention in a sectional and a perspective view, Fig. 8 magnetic field lines in a magnet unit of an inspection device according to the invention and an object to be inspected, Fig. 9 a magnet unit of a further object according to the invention.

[0030] Individual technical features of the exemplary embodiments described below can also be combined with previously described exemplary embodiments as well as the features of the independent claim and, if applicable, further claims to form subject matter according to the invention. Where appropriate, functionally equivalent elements are provided with identical reference numerals.

[0031] In the future, Fig. 1 a part of a spacer 1 of an inspection device according to the invention, comprising a magnet unit 3. The spacer 1 comprises a housing 2 in which the Fig. 3 recognizable magnet unit 3 is housed. The housing 2 is with the side facing the surface of the object to be inspected in the Fig. 1 Shown facing upwards. A distance to the object is set via a wheel 4, which is rotatably mounted in a fork 6. Two sensors 5, each designed as a transmitting and receiving transducer, serve to generate and record measurement signals. At the opposite end of the spacer 1, another fork 8 is shown, which can be mounted on a support frame of an inspection device according to the invention and / or optionally provided with another wheel.

[0032] The magnet unit 3 has two magnets 10, the magnetization directions (north-south direction) of which run parallel or at least approximately parallel to the longitudinal direction F, which corresponds to the main direction of movement of the inspection device during operation, and the north pole sides 12 of which face each other ( Fig. 2 ). With respect to the magnet unit 3, the Fig. 2 the direction arrow on the side of the surface to be inspected during operation.

[0033] At the same time, both north pole sides 12 rest against a focusing element 14. On its side facing the direction arrow F, another magnet 18 rests with its north pole side 16 against this focusing element (cf. Fig. 3 ). This magnet 18 has a magnetization direction that is tilted or angled by 90° to the magnetization direction of the magnets 10.

[0034] In the longitudinal direction of the magnet unit, which runs parallel to the arrow F, the magnet unit has enclosures 20 which are constructed from a magnetizable material, preferably a steel comprising cobalt and iron, wherein the enclosures 20 delimit the magnets of the magnet unit 3 in such a way that they adjoin them in the longitudinal direction at the front and rear.

[0035] The focusing element 14 is also made of a steel comprising cobalt and iron. Due to its outward arrangement, away from a bottom side 15 and toward the surface of the object to be inspected, the focusing element 14 achieves flux densities of preferably 2 to 3 Tesla. The magnetic flux is forced by the magnet 18 through the focusing element 14, which is designed as a steel element, in such a way that the magnetic field lines are focused toward the object. While standard Halbach arrays are limited in their maximum application of the magnetic field by the saturation flux density, the inventive design of the inspection device increases the attractive force by a factor of at least 3, as described above. Weight and costs can therefore be kept correspondingly low.In the embodiments shown in the figures, the segments of the magnet units are each formed by a magnet, which then also determines the magnetization direction of the respective segment.

[0036] On one side of the magnet unit 3 there is an inner enclosure 22 which additionally shields the already almost negligible magnetic field of the magnet unit 3 in this direction.

[0037] The magnet unit after Fig. 1 is complementary in Fig. 3 Such a magnetic unit, together with the sensors 5, forms part of a functional unit for recording object information in the form of sensor data.

[0038] An inspection device according to the invention according to Fig. 4 is provided with a handle 27, which represents the upper end of a guide device having a guide rod 29, by means of which the inspection device can be moved by an operator 31 in direction F along a surface of an object 32 to be inspected in the form of a metal sheet. For example, this is a lower boundary or wall of an oil reservoir.

[0039] The functional unit of the inspection device further comprises the sensors 5 and, in the additional housing 33, means for signal generation and evaluation. The sensors 5 are, in particular, EMAT-WT sensors, i.e., sensors for electromagnetic-acoustic measurement of the wall thickness of the object 32.

[0040] A magnet unit 3 of a further inspection device according to the invention with a larger number than three magnets is shown in the Fig. 5 Focusing elements 14 are arranged here on the north pole sides of the adjacent magnets 10 and 18, respectively. A further focusing element 14' is correspondingly limited by the south pole sides of the adjacent magnets. In addition, a magnet unit as already described can Fig. 6 shown frame 20.

[0041] Fig. 7 discloses in the two figures there an alternative design of a magnet unit 3. The Fig. 7 The top right figure shows a perspective view, while in Fig. 7 A corresponding cross-section is shown at the bottom left. A hemispherical focusing element 14 is defined by a single- or multi-part magnet 10 with a circular cross-section, which in turn is arranged within a casing 20. The hemispherical steel casing 20 serves as a magnetic return path.

[0042] The magnetic field lines that arise in a magnet unit 3 and the object 32 arranged close to it during operation are shown in the Fig. 8 symbolized by black, acute-angled triangles. A sensor 5 is present in this case, but not shown. The triangles are located in the Fig. 8 in the cells of a triangular grid created based on the computational simulation of the magnetic field lines of both the magnet unit 3 and the wall of the object 32. The stronger the gradients of the magnetic field lines in terms of direction and / or amplitude, the finer the resolution and the smaller the cells of the grid. The magnetic flux densities present in the focusing elements 14, 14' are particularly large, symbolized by correspondingly large triangles.

[0043] A magnet unit, which is particularly well suited for use in an inspection device designed as a self-contained hand-held inspection device, additionally has magnets on the sides, which continue to focus and amplify the magnetic field on the focusing element 14 in the manner described above.

Claims

1. An inspection device for inspecting metallic objects (32) extending in planar fashion, in particular sheets or walls, the inspection device being embodied as pipeline-impassable in particular by virtue of dispensing with at least one propulsion element that at least substantially fills an inner pipeline cross section, comprising at least one functional unit for recording object information and also comprising at least one magnet unit (3) provided for magnetizing the object and having a plurality of magnets (10, 18), wherein the magnet unit (3) has a plurality of segments each having at least one magnet (10, 18) and the magnetization directions of segments adjoining one another are angled approximately by 90°, relative to one another.

2. The inspection device as claimed in claim 1, wherein the magnet unit (3) has magnets (10, 18) embodied as permanent magnets, the poles (N, S) directed towards one another of two segments separated by a further segment having an identical polarity.

3. The inspection device as claimed in claim 2, wherein the segment arranged between the two segments as a vertical segment has, during operation, a magnetization direction which is directed in the direction of a surface of the object (32) to be inspected and which is preferably formed at least approximately perpendicularly thereto.

4. The inspection device as claimed in claim 3, wherein the vertical segment is bounded by a focusing element (14) towards the surface of the object to be inspected.

5. The inspection device as claimed in claim 4, wherein the focusing element (14) is bounded by a magnet (10, 18) on at least three sides, the poles of the magnets (10, 18) that are situated on these sides having an identical polarity.

6. The inspection device as claimed in any of the preceding claims, wherein the magnet unit (3) in a longitudinal direction parallel to the surface of the object to be inspected, has at least one surround (20) which is at least concomitantly formed from a magnetizable material and which bounds the magnets (10, 18) of the magnet unit.

7. The inspection device as claimed in any of the preceding claims, wherein the magnet unit (3) has a sensor (5) for recording inspection data.

8. The inspection device as claimed in any of the preceding claims including claim 4, wherein the sensor (5) is arranged in the focusing element (14), in a recess thereof and / or on the focusing element (14).

9. The inspection device as claimed in any of the preceding claims, wherein the magnet unit (3), in the longitudinal direction thereof, has at least three magnets (10, 18) arranged one behind another.

10. The inspection device as claimed in any of the preceding claims, wherein a plurality of magnet units (3) are arranged next to one another in particular in order to cover a curved contour of the object.

11. The inspection device as claimed in any of the preceding claims, characterized by at least one in particular adjustable spacer (1) which allows the magnet unit (3) to be positionable at a distance from the surface of the object (32).